Hello,

This patch brings in the last big change sitting on the reggroups branch.

It adds regcache save/restore functions to to the regcache.
These functions save/restore a subset of registers determined by the 
save/restore reggroups (by default REGNUMs in the range [0 .. NUM_REGS) 
are in both the save_reggroup and restore_reggroup, and hence are 
saved/restored).

As part of this, a saved read-only regcache is expanded so that it can 
hold the saved value of any register in the full [0 .. 
NUM_REGS+NUM_PSEUDO_REGS) range.  This is so that architectures with 
memory-mapped registers (which fall into the range [NUM_REGS .. 
NUM_REGS+NUM_PSEUDO_REGS) have somewhere to save them.

I'll look to commit it in a few days,

(Oh, and it deletes the last remaining core reference to 
read_register_bytes() or write_register_bytes()).

Andrew