Rename regs (remove .r and .n suffix for reg types). [Not for merging]

Regs can now be accessed directly by name or by array index when specifying the reg type.
This removes a lot of the 'fluff'.

Any discussion on renaming of regs is welcome.

Only GPR and CP0 use named entries. The names are quite different and relate to actual reg functions, so hard to be confused. Even so, perhaps the names should be changed in some instances.
It would likely be better as an enum.
Oh I see, I guess debuggers will dump it easier that way.  I usually just use an immediate if I'm after a particular reg, but I can see how that'd be easier.

Would still work with the struct I mentioned, though.

I see almost no usage of .v0 etc. though.

-[Unknown]