* add getSignedIntIterator to roaring bitmaps and use integers above 2^31 in the test iterators.

We sometimes use roaring bitmaps for iterative filtering where the opposite side of the join is sorted using signed comparison. Create a function to peekable int iterator to more easily allow that.

* comment cleanup

* comment cleanup

* @zoltanmeze caught that I meant we skip to the negative numbers when doing a signed int sort, not positive numbers. fixup comment.

* adds failing test for issue 730

* fixes BitmapBatchIterator.hasNext to return accurate result for empty containers

…ting container index (#734)

* Use advanceUntil to find starting container index

* Allow advanceIfNeeded to wrap around in signed int iterators

* Simplify finding starting container index

* Step down container index if next present container key is larger than target container key

This means that previous value (if exist) must be always in the previous container

* Return value as unsigned long when previous value is also the last (largest) value in bitmap

* Remove unnecessary condition

* Skip empty words while iterating over bitmap container in RunContainer#contains(BitmapContainer)

* Format

* Implement first and last signed methods

Allows retrieving minimum and maximum signed integers from bitmap

* Remove unnecessary (duplicate) javadoc