SVC: Return correct error code on invalid CreateThread processor ID.

SVC: Assert when creating a thread with an invalid userland priority.

Also fixes descriptions in the process.

Also gets rid of preprocessor mumbo-jumbo

The switch cases will always be hit, but this makes compilers stop complaining.

The background color can be seen at the sides of the bottom screen or when the window is wider than normal.

Also implements writing to the rest of the ARM11 MPCore CP15 register set.

Keeps everything contained. Added all supported readable registers in an ARM11 MPCore.

Decode is a static function. There's no need to allocate a disassembler instance.

It's a generic helper function, so it should be here anyway.

We don't need to care about XScale or Intel specific ARM stuff.

In CreateExtSaveData, DeleteExtSaveData and CreateSystemSaveData

with a stub for GetSoundVolume

Rephrased some comments.

Removes a TODO.