Reasons: 1) It's unsafe - we cannot guarantee that address is still good
while it is used. 2) It's wrong in many modules which are usually just
compare pointer with zero.
* Added a loader for the TROPUSR.DAT files.
* Added a few structs/enums to sceNpTrophy.h
* Added more sceNpTrophy functions and updated other ones.
* Updated cellHddGame error codes in cellSysutil.h
* Added addresses of cellHddGame to cellSysutil_init.
NOTE: There is a known problem in the `if
(!Emu.GetVFS().ExistsFile(filepath))` in `TROPUSRLoader::Load` which
causes the games to overwrite their TROPUSR.DAT file every time they
boot and they "forget" the unlocked trophies. However, as long as the
game is running the unlocked trophies should be still there.
