* register allocation is now handled by a class and is mostly processor
independent (+rgobj.pas and i386/rgcpu.pas)
* temp allocation is now handled by a class (+tgobj.pas, -i386\tgcpu.pas)
* some small improvements and fixes to the optimizer
* some register allocation fixes
* some fpuvaroffset fixes in the unary minus node
* push/popusedregisters is now called rg.save/restoreusedregisters and
(for i386) uses temps instead of push/pop's when using -Op3 (that code is
also better optimizable)
* fixed and optimized register saving/restoring for new/dispose nodes
* LOC_FPU locations now also require their "register" field to be set to
R_ST, not R_ST0 (the latter is used for LOC_CFPUREGISTER locations only)
- list field removed of the tnode class because it's not used currently
and can cause hard-to-find bugs
