Problem: New regexp: End of matching pattern not set correctly. (Cesar
Romani)
Solution: Quit the loop after finding the match. Store nfa_has_zend in the
program.
Problem: Syntax highlighting can be slow.
Solution: Include the NFA regexp engine. Add the 'regexpengine' option to
select which one is used. (various authors, including Ken Takata,
Andrei Aiordachioaie, Russ Cox, Xiaozhou Liua, Ian Young)
