The global setting was causing fragility other places requiring include order
to be specific. Remoed the global "#pragma pack(4)" and replaced it with the
equally ugly "__attribute__((packed, aligned(4)))", but at least it is explicit
and doesn't interfere with system and 3rd-party header files and libraries.
Origin: e4323f397f
disk space. added tagdb file cache for better performance,
less disk accesses. will help reduce disk load.
put file cache sizes in master controls and if they change
then update the cache size dynamically.
