dynamically extensible

  into other nodes
- correctly fix Copies in x87 simulator

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

Adapted to the new dependency edges

- Cleanup remat code a little bit
- Adjust remat cost limit to new costs in ia32 backend
- Don't spill unused livethroughs around blocks anymore in bespill_morgan
  (but only around loops), this makes the code faster smaller and the results
  slightly better as belady performs better for basic blocks

- Make ia32_Push and ia32_Pop return their stackpointer adjustment
- replaced stack_dir enum + unsigned offsets with normal integer offsets
- make schedule verifier detect dead nodes in schedule

- Stackparams get rematerialized now
- several warning fixes

Adjusted abi construction for alloca's

- No need to set strange spillcontexts on spills anymore
- Spillcontexts are now assigned and coalesced in a separate pass after spilling/register allocation of all register classes
- There might be cases where the new code inserts memcopies, these are not implemented in the ia32 backend yet

blocks or loops). Other small changes:

* Added some verify functions that check for register pressure or valid schedules (replaces the broken check_pressure in bechordal_main.c)
* Some style/readability improvements to the belady spill code
* Some style/readability improvements to beuses.*
* Fixed registerpressure stat dumper
* Some improvements to bespill.c: When spilling already reloaded values, don't add a 2nd spill.