* 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.
* Better automatic conversions to and from tagged uint160 varints.
* Start using tagged variants of uint160 for Currency, Account.
* Comments from 2014/6/11 RippleCalc session.
* Rename many variables.
* Make most of PathState private.
* Extract out common Node::isAccount() code.
* Rename bConsumed to allLiquidityConsumed_.
* Extract out code into PathState::clear().
* Rename unity files
* Move some modules to new subdirectories
* Remove obsolete Visual Studio project files
* Remove obsolete coding style and TODO list