- more work on state registers for x87 fpu rounding modes

- Replace limit callback in register requirements with a simple bitset
- Fix backends, generators and the rest of the code for the change register
  requirements structure
- Eliminated the custom register_requirement structures in the backend, they
  are pointless now, use the normal arch_register_req_t
- Fix TEMPLATE backend
- Extract emitter framework from ia32 and provide generic header/code for it
- Port TEMPLATE backend to new emitter
- Extract gas specific emit stuff (declarations, sections) from ia32 backend
  and provide it as generic header/code. Make TEMPLATE backend use that
- Remove several FIRM_DBG_REGISTERs from functions which are called very often.
  Before we had millions of string hashtable lookups because of that. The
  prefered way is to have 1 static debug module per file and initialize it in
  the module constructor. No passing around in environment structs and in no
  case should you dynamically register it in single functions.

- typo fixed

  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