additional tests

  Add three test-cases from ansi-cl-tests that used to break stack
  analysis.

  Uncomment one old test that no longer fails.
Fix a regression in LOOP.

(loop for i from #c(1 2) ...) is legal. I would think that
(loop for i from #c(1 2) to #c(5 2)) should work to, but everybody seems to
agree that it shouldn't, so I left it not working.

Found out by ansi-cl-tests.
Fix LOOP sum x of-type complex.

A regression during recent changes.

Found out by ansi-cl-tests.
Fix LOOP REPEAT on negative integers.

A recent regression caught by ansi-cl-tests.
Fix LOOP with character types.

(loop with a t return a) returned #\x, do that only if the type is a
subtype of character.

Caught by ansi-cl-tests.
Refactor FLUSH-WHITESPACE
fix test for bug-351

   Wasn't testing what it was supposed to test: instead
   of hitting the malformed code from the SETF LET, it
   died on the invalid argument count instead. Oops.
allow using optional arguments in DEFERR handlers

   Unused for now, use coming in next.
include function name in errors about invalid local calls

  They call won't appear in the backtrace, so it really needs to be in
  the error message to avoid confusion -- prior to this the
  information about which function was the responsible one was hidden
  in the compilation log.
update .mailmap so 'git shortlog' is prettier