streams.h has some methods that can be tricked into dereferencing
null pointers or end() iterators. Fix this.

Some minor github-merge improvements I've made over time:

User interface:

- Print merge details again before signing off, to refresh your memory -
  usually I'll have done lots of different things in the shell so this
  will have scrolled out a long time ago.

- Require a valid answer on the prompts. One of the requested answers
  must be typed, if not, the prompt will re-ask. This prevents
  accidentally rejecting.

Efficiency:

- Condense "accept merge" and "sign off" prompts. There's no reason to
  have this as two separate prompts, both are just opportunities to skip
  out on the merge, no action is performed in between.

Merging:

- Strip spaces from github title. This avoids redundant spaces
  surrounding it from getting into the commit message.

821dd5e Tests: Add test for getdifficulty (Jimmy Song)

Tree-SHA512: 3da78c4f88efdaab8374582cda606620beb2f1e9a93119a72b67572702c17c36b68c3abf9d466e8c7fb8ba9e8afa9a172e454c553df10d3054f19b3282d3097b

…n function

c39a6b9 Tests: Refactor to create witness script creation function (Jimmy Song)

Tree-SHA512: 1dde621c811ea1a2719acb9a9b84825d3f520234da7fc4045da13754d4a6e6736de2fd508a2b6e64226ad95c7e634bf76d36bd0dcd1b37c63e7b1e172ee0816c

f478d98 Fix some empty vector references (Pieter Wuille)

Tree-SHA512: a22022b9060cd39f8d349e8dd24490614c0028eae2fbc7186d0d26b1d47529049b2daee41f093c0722130274a0b6f7f8671c2295c8cb4a97028771eaff080734

…ions()

25660e9 pass Consensus::Params& to ReceivedBlockTransactions() (Mario Dian)

Tree-SHA512: d3a5b19d93313e4bda622b322bc9cbfb7e31486010eac40fca6eea9703f814f9667f778122ba7366bb304482a2c03e2e3325083beecac374751692361952e467

dd07068 Fixed typo in documentation for merkleblock.h (Mikerah)

Tree-SHA512: 92655c8022eb33852c116da517b12bd17b3b668713cd85fe185a15245ea9810605626b1d0955fa117f7b56863e0a52b3a86dab42409332452b5eb72a7d34f30d

bc53752 Tests: Add simple test for getaddednodeinfo (Jimmy Song)

Tree-SHA512: d2f8a384fb994b83f881b585db70e7cf57980821074126d254960cb67988a40672ffde065d0ccd9a90f9e3b395d8cd33695c796ecb4b54f69fe74ee2bf7497a6

…ty covered by other test)

5f4bcf2 [tests] Remove maxblocksinflight testcase (John Newbery)

Tree-SHA512: 827c8b12f4b52684a973bbfc508c5906e640572e22a96b9420a7aea86ad8d4aa4d6fcc2bb091f747e2fdd18c897e0456baff254bd5e3ceaf721bd3f09a2fd60b

…t case.

6803e09 Move zmq test skipping logic into individual test case. (John Newbery)

Tree-SHA512: 9d166b53e9acf386c4dafc860b38e2901b331a7505bba9714a2f4e3bdef68b0316c8b76fddbfb620835ddee549cf32fffb3a96a19b0799ad94f2553f55f19a35

…ha20

4fd2d2f Add a FastRandomContext::randrange and use it (Pieter Wuille)
1632922 Switch FastRandomContext to ChaCha20 (Pieter Wuille)
e04326f Add ChaCha20 (Pieter Wuille)
663fbae FastRandom benchmark (Pieter Wuille)
c21cbe6 Introduce FastRandomContext::randbool() (Pieter Wuille)

Tree-SHA512: 7fff61e3f6d6dc6ac846ca643d877b377db609646dd401a0e8f50b052c6b9bcd2f5fc34de6bbf28f04afd1724f6279ee163ead5f37d724fb782a00239f35db1d

…ions

911a480 wallet: Add comment describing the various classes in walletdb.h (Wladimir J. van der Laan)
69d2e9b wallet: Make IsDummy private in CWalletDBWrapper (Wladimir J. van der Laan)
3323281 wallet: CWalletDB CDB composition not inheritance (Wladimir J. van der Laan)
be9e1a9 wallet: Reduce references to global bitdb environment (Wladimir J. van der Laan)
071c955 wallet: Get rid of fFileBacked (Wladimir J. van der Laan)
71afe3c wallet: Introduce database handle wrapper (Wladimir J. van der Laan)

Tree-SHA512: e4e72953c61a2f6995d609a32f8ed8e18cab9a92bc9e193d46a1d1f06d9daa5c6da6fce2867d4e3ba4fc0439141901a3d35f246486f0fa8f59587786379dfcbd

e6756ad Switch CCoinsMap from boost to std unordered_map (Pieter Wuille)
344a2c4 Add support for std::unordered_{map,set} to memusage.h (Pieter Wuille)

Tree-SHA512: 51288301e7c0f29ffac8c59f4cc73ddc36b7abeb764009da6543f2eaeeb9f89bd47dde48131a7e0aefad8f7cb0b74b2f33b8be052c8e8a718339c3e6bb963447

…LogPrintf call.

…alized

5ec8836 Prevent warning: variable 'x' is uninitialized (Pavel Janík)

Tree-SHA512: 54e39d4b85303db033bd08c52ff2fa093ec9a1b1b9550911bb2123be60fa471cba81f36859681170695dfafb3a8a4c154122917c05b5a23837cf97c25907afc1

93dbb15 Remove Clang workaround for Boost 1.46 (fanquake)

Tree-SHA512: 1246841b264688f5fe5a2a514dd732d400307fa068686857e8aedaebb292ae65b21ab96b5ff9477ccd2f049882b967b6e143683963ce1be0b9e781596c5372d1

94807be Trivial: fix fee estimate write error log message (CryptAxe)

Tree-SHA512: 998c9b331e901562c9ba575a85bc6c66f28d926dfe8116f08ab903e024c63a13fd37a58d19eb6504ad880d5bbccfbf6cba83ba0a6917f5d9068c52114f71b437

… potentially referencing

c36ea69 [wallet] Make sure pindex is non-null before possibly referencing in LogPrintf call. (Karl-Johan Alm)

Tree-SHA512: a14c9f3e1228bca91977bea821c56a377d80889b41d250050c9be67aa93e460319a7cf1d4b63ee40f23b5a34159590f0e3fe15dc88698dc694c0c8098bd2db4d

ed60970 [test] Test abortrescan command. (Karl-Johan Alm)

Tree-SHA512: 7f617adba65a6df8fdc4b01432992926a06c4a05da4e657653436f7716301fa5d6249d77894a097737e7fb9e118925883f2425c639058b8973680339bb8e61b6

1b936f5 Replace boost::function with std::function (C++11) (practicalswift)

Tree-SHA512: c4faec8cf3f801842010976115681f68ffa08fbc97ba50b22e95c936840f47e1b3bd8d7fd2f5b4e094b5a46bf3d29fc90b69d975a99e77322c0d19f8a00d53d3

ad415bc [net] Added SetSocketNoDelay() utility function (Thomas Snider)

Tree-SHA512: c19e3c9910b3fc2ef86f2434f3e91d343e9cd9e2116153941de9789e2a6fc0389bffe762d21b55cda4a4b1de993afee0564c6946e65d05cef9e866b58896f9af

64aa36e param variables made const (ロハン ダル)

Tree-SHA512: 7c19f9e7dd574c8ce8a9468555f27196735b583efe349c1309c90e1e5d2949daf6891574b4bea7122d6c6aca0c7ee4a782fe3d24918d889f7bf89227084a51cd

a387837 Make sure we re-check the conditions of a feebump during commit (Jonas Schnelli)
9b9ca53 Only update the transactionrecord if the fee bump has been commited (Jonas Schnelli)
6ed4368 Make sure we use nTxConfirmTarget during Qt fee bumps (Jonas Schnelli)
be08fc3 Make sure we always update the table row after a bumpfee call (Jonas Schnelli)
2678d3d Show old-fee, increase a new-fee in Qt fee bumper confirmation dialog (Jonas Schnelli)
2ec911f Add cs_wallet lock assertion to SignTransaction() (Jonas Schnelli)
fbf385c [Qt] simple fee bumper with user verification (Jonas Schnelli)

Tree-SHA512: a3ce626201abf64cee496dd1d83870de51ba633de40c48eb0219c3eba5085c038af34c284512130d2544de20c1bff9fea1b78f92e3574c21dd4e96c11b8e7d76

49a199b torcontrol: Handle escapes in Tor QuotedStrings (Jack Grigg)
0182a11 torcontrol: Log invalid parameters in Tor reply strings where meaningful (Jack Grigg)
0b6f40d torcontrol: Check for reading errors in ReadBinaryFile (Jack Grigg)
d63677b torcontrol: Fix ParseTorReplyMapping (Jack Grigg)
29f3c20 torcontrol: Add unit tests for Tor reply parsers (Jack Grigg)
d8e03c0 torcontrol: Improve comments (Jack Grigg)

Tree-SHA512: aa3ce8072d20299b38c4ba9471af7fab1f5df096c237bf40a96ee9274a357f7366f95ced0cc80f8da1f22f6455a1a8e68bad9a5ff71817eef3397b6aefcbc7ae

…cation

618d07f MOVEONLY: tx functions to consensus/tx_verify.o (Jorge Timón)

Tree-SHA512: 63fa2777c070a344dbfe61974526a770d962e049881c6f371b0034b1682c1e6e24f47454f01ee35ded20ade34488e023d4467a05369662906b99a73bb5de8497

When inserting two addresses of the same class, from the same source, they have
a 1/64 chance of colliding.

2300a5e [Trivial] Add BITCOIN_FS_H endif footer in fs.h (Ahmad Kazi)

Tree-SHA512: fd56c5c78c12db74baeef93186b59814ac626beeecfad5db852ab8eaad8e71f7f47d64590bcdd9052cc9e97f4531ba90c1f66f0f9e6517d2f956d622803111df

6b51b0a tests: fix spurious addrman test failure (Cory Fields)

Tree-SHA512: 3d41723b1a31ff459d950331ffea7f383e4ef6187990be6a634978bead0c29d7c096f68e7edb6d4dc56069c1fe8a6f12a6daf573cb1e542b15d000eaa54ad288

* Add SCDB to track sidechain WT^ work score

* Add coinbase cache to track N recent coinbases. Used both to synchronize SCDB and BMM linking data

* Add OP_BRIBE and OP_BRIBE activation

* Add wallet function to create sidechain desposits which have unique requirements

* Miner broadcasts WT^ in block if workscore is made sufficient

* CheckWorkScore code

* Initialize everything during AppInit

* Added sidechain address prefix to be used

* Added testing list of valid sidechains test, hivemind, mimble wimble

* receivesidechainwtjoin

* listsidechaindeposits

* getbmmproof

* createbribe

* refundbribe

43c5877 Prevent shadowing the global dustRelayFee. (Pavel Janík)

Tree-SHA512: 9765931a7753c484990003396afd0bb65a53f42d1cad9502017720618ce90b3c5ae68591db01e3524adecdbe6925a5eeeebf04012ba644ef3b65073af207ae5d

b040243 [tests] improve tmpdir structure (John Newbery)

Tree-SHA512: b21ad555c3c23a43087b893ad18bd2398e1df91b82c0bf1804d07fdb582600a1c339e6f4aaca58074e52f146f459943a0e492abc045b2666d4a3a7e0e455d6dd

* Add sidechain deposit button to sendcoinsdialog

* Add sidechain deposit dialog

Add Drivechains & BMM to bitcoin core

* Add GetBWTHash() function to CTransaction so that we don't have to manually
blind the transaction when checking work score.

* Update comments to make them more clear and add TODO messages about what
still needs to be finished in AcceptToMemoryPoolWorker().

* Update comments & code in connect block where WT^ workscore is
verified

* Update rpc client param conversion

* Update createbribe rpc function (WIP)

* Update IsBribe()

* Add BMM ratchet unit tests

* Enforce BMM ratchet block number rules

…#10)" (#12)

This reverts commit 4eb5c1d.