walking occurs before finish phase now
- changed ia32 to do some things transforms from finish phase in after_ra phase
  already but do peephole optimization in finish phase.
- Added a peephole optimisation that transform IncSP,Store cascades to
  Pushs
- Replaced several HASH_PTR with nodeset_hash to make compiler more
  deterministic.

backend options can then be read from arbitrary files

handle be_Copy(Const)

- warning fixes

Cosmetic changes

 - fixed call to get_irg_estimated_node_cnt()
compiles with WITH_LIBCORE disabled again

be_Call is now a fragile op (like Call). This allows ProjX from Call nodes to the End node even in backend.

removed code for create_Pop: need to be reimplemented