Unit tests would fail if compiled with -DDEBUG_LOCKORDER (AssertLockHeld()
would fail; AssertLockHeld() relies on the DEBUG_LOCKORDER code to keep
track of locks held).
Fixed by LOCK'ing the wallet mutex in the unit tests that manipulate the
wallet.
Use misc methods of avoiding unnecesary header includes.
Replace int typedefs with int##_t from stdint.h.
Replace PRI64[xdu] with PRI[xdu]64 from inttypes.h.
Normalize QT_VERSION ifs where possible.
Resolve some indirect dependencies as direct ones.
Remove extern declarations from .cpp files.
AvailableCoins() makes a vector of available outputs which is then passed to SelectCoinsMinConf(). This allows unit tests to test the coin selection algorithm without having the whole blockchain available.