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.
For backward compatibility, new accounting data is stored after a \0 in the comment string.
This way, old versions and third-party software should load and store them, but all actual use (listtransactions, for example) ignores it.