Hello,

This is is the first pass of converting the MIPS to the new frame code. 
  This pass gets the MIPS using the new framework (but with a hybrid 
heuristic + proc_desc unwinder).  Later passes will gut much of the now 
dead code, and split things into two unwinders.  I've committed it now 
cos the 64-bit results are sooo much better (like it works) - not bad 
for an afternoon hack.

Note that it still lacks sigtramp unwinders.

Andrew