fix source information for functions from EVAL

fix source information for functions from EVAL

 * Removed the breathtaking (NAMED-LAMBDA (EVAL (DEFUN FOO)) ...) hack, which
   caused inconsistent source locations, and broke the built-in debugger
   source command for evaluated functions.

   Replace it with *SOURCE-FORM-CONTEXT-ALIST*, which allows the simple
   evaluator to communicate the original context to the compiler without
   messing with the function source.

   This also means we no longer have to wrap named-lambdas and lambdas in
   another lambda, but can instead compile them directly -- which in turn
   allows FUNCTION-LAMBDA-EXPRESSION to work correctly for definitions from
   EVAL and LOAD.

 * Additionally, use a handler to muffle any compiler notes from EVAL instead
   of using a declaration: those can leak to the user via F-L-E.

 * Change ACTUALLY-COMPILE to return a function signaling an error instead of
   returning NIL when compilation fails fatally. Doing this in
   ACTUALLY-COMPILE allows us to rely on COMPILE-IN-LEXENV always returning a
   function, and gives easy access to a better error message.

 * Properly associate COMPILER-ERRORS with their SIGNAL-ERROR restart.

 * Adjust debug.impure.lisp to be less dependent on the details of
   %SIMPLE-EVAL.

 * Test cases. Pay special attention to TEST-DEBUGGER in debug.impure.lisp.

 * New docstring for COMPILE. Added a sneaky teaser about COMPILE being able
   to recompile things, which is new starting to look feasible.