Add helper functions for reimplementation of font-lock-keywords
Major refactoring of font-lock-keywords:

- add highlighting of local var assignments with multiple variables
  local x,y,z = ...

- simple on-fly syntax check in local var assignments
  local 00xyz, foo, bar,, baz bux = ....
        ^^              ^     ^^^
        these are syntax errors and will be highlighted

- faster and more precise function name matching

- fix docstring; it was inside (eval-when-compile ...) block and hence
  considered one of the font-lock rules :)
Add var name highlighting in "for x,y in ..." construct
Improve local var assignment matching

- make sure == is a syntax error
- make sure names are matched on symbol boundaries
Add field containing commit SHA expanded during archive creation.
Bump copyright information (no luck with FSF), rephrase comment