Remove optimization declaims
Add standard SBCL file headers.
Make a simpler entry point, instead of using the EVAL-MC guts directly in eval.lisp
Minimally compiled functions are compiled functions
Fix handling of required parameters that are also globally special
Resignal compiler-errors as program-errors
Track optimization policy in EVAL-MC contexts

While the minimal compiler doesn't need access to the policy itself,
they're needed when we construct SB-C:LEXENVS to give to macroexpanders.
Kill a weak hash table in minimal compilation

- Used for mapping source to source paths
- Make it a normal hash table, but with an extent of a single call to
  eval-in-native-environment
Only set the source path for a closure if a path actually exists

- No point in storing NILs in the hash table
- More importantly, it's possible for %PREPARE-FORM to return a
  closure that already has a source path stored. We don't want to
  overwrite it with a NIL if no source path can be found in
  PREPARE-FORM.
Fix debugging nested interpreted calls

- Need to check for whether the next frame is an interpreted-frame in
  addition to the check for whether it's a non-interpreted-frame for a
  sb-eval-mc::minimally-compiled-function.
- Also comment the debug-int changes a bit.
Kill the global weak hashtable closure -> source info mapping

- Instead store a smaller non-weak mapping in the
  MINIMALLY-COMPILED-FUNCTION, and jump through a couple of hoops to
  get access to the function object in the debugger.
- Speeds up a ansi-test run from 63s to 45s.
Make just a single SB!C:SOURCE-LOCATION per evaluator call

- 70% of minimal compilation time was spent on just string concatenation
  for namestrings ;-)
Create just one native lexenv per SB-EVAL-MC context
Optimize conversion of progn forms
Add a first-class implementation of BLOCK / RETURN-FROM instead of macros

- Avoids a useless CATCH at runtime in the common case of implicit
  blocks being unused.