Cherry-picking

• ea73b84 Add src/interface/README.md
• 71e0d90 Remove direct bitcoin calls from qt/bitcoin.cpp
• c0f2756 Remove direct bitcoin calls from qt/optionsmodel.cpp
• 3d619e9 Remove direct bitcoin calls from qt/bitcoingui.cpp
• c2f672f Remove direct bitcoin calls from qt/utilitydialog.cpp
• 5fba3af Remove direct bitcoin calls from qt/splashscreen.cpp
• fe6f27e Remove direct bitcoin calls from qt/clientmodel.cpp
• d7c2c95 Remove direct bitcoin calls from qt/intro.cpp
• e0b66a3 Remove direct bitcoin calls from qt/peertablemodel.cpp
• 3034a46 Remove direct bitcoin calls from qt/bantablemodel.cpp
• 582daf6 Remove direct bitcoin calls from qt/rpcconsole.cpp
• 90d4640 Remove direct bitcoin calls from qt/optionsdialog.cpp
• a0704a8 Remove most direct bitcoin calls from qt/walletmodel.cpp
• 827de03 Remove direct bitcoin calls from qt/coincontroldialog.cpp
• 3ec2ebc Remove direct bitcoin calls from qt/addresstablemodel.cpp
• 3cab2ce Remove direct bitcoin calls from qt/paymentserver.cpp
• 5884558 Remove direct bitcoin calls from qt transaction table files
• e872c93 Remove direct bitcoin access from qt/guiutil.cpp
• 56f33ca Remove direct bitcoin calls from qt/sendcoinsdialog.cpp
• 9a61eed Use WalletBalances struct in Qt
• 9960137 Add developer notes about blocking GUI code

Additional Stuff:

• Privatesend stuff everywhere
• InstantSend stuff at least in clientmodel
• Masternode list stuff in clientmodel