Lots of post-CFEM-quadrature changes.

Implement user control over slab decomposition.
Use CSEs instead of register prefetch.
Remove CodeGenerationState.
Carry CSE replacement info in CodeGenerationMapper.
Carry CCM in ExecutionDomain.
Allow user to specify (unchecked) assumptions on parameters,
  to avoid unnecessary conditionals.
Parse desired operation from strings, extract CSEs.
Support for equality constraints in for loops.