Remove rockdb subtree
Squashed 'src/rocksdb/' content from commit 78b8a7d

git-subtree-dir: src/rocksdb
git-subtree-split: 78b8a7d908d7e67cc6664398e39560b76c965773
Merge commit '7bfb4a9ba5a2822f7d9ef7122b1388aea4be9404' as 'src/rocksdb'
Update rocksdb unity file
Remove recursions from computeLiquidity
Rename RippleAsset to Issue and RippleBook to Book:
* Split STAmount out of SerializedTypes.h
* New concept of "Issue consistency": when either both or neither of its
  currency and account are XRP.
* Stop checking for consistency of Issue in its constructor.
* Clarification of mIsNative logic in STAmount.
* Usual cleanups.
Pathfinding Documentation
SHAMap Documentation
Patch Boost to suppress warnings on clang