Revision 1265: Implemented signal handling in GE commands: SIGNAL command, sceGeContinue. This might reveal graphics in some games (e.g. when displaying "END without FINISH"
or "Unsupported sceGeContinue").
Avoid displaying "Unknown/unimplemented video command [0xFF]" before BOFS
command.
Revision 1264: Fixed read64 (spotted by i30817).
Revision 1263: Fixed sceKernelUSec2SysClockWide (reported by i30817).
Added fake return value to sceKernelReferLwMutexStatusByID.
Revision 1262: Better checks for ringbuffer being null (reported by i30817)
Added fake return value to sceKernelReferLwMutexStatusByID.