Add pygments parser option

global now builds a pygments parser by default. Make this work with a --with-pygments option to the recipe.
Got it, that worked!

So pygments is really only useful as a plugin parser when combined with exuberant-ctags (it will run without it, but then it indexes everything as other-symbols vs. the more expected/useful definitions, references and other-symbols. Should —with-pygments auto-set —with-exuberant-ctags? If not should we issue a warning? Is there an example of whichever method we should use I can look at?

Thanks,
Chris.