Add TAP syntax file

Thanks to http://github.com/threebytesfull
Make note of tap.vim in Changes
Move LAST_CHANGE substitution into separate script
Add LAST_CHANGE to tap.vim
Remove regexpengine override

The NFA regexpengine is stable enough to work for us now
Remove foldmethod setting in Perl 6 syntax
Remove very specific bug fix

This only occurs for Vim 7.1.000 - 7.1.220.  Vim 7.2 was released
six years ago, and I'd rather not keep cruft around for code older
than that.
Add simple timing script
Merge commit '2d87000ea7575fec94da8c595a0fdbb9c8f6cd63'