Praat syntax highlighting rules

Adds syntax highlighting for [Praat](http://www.praat.org), a GPL acoustic analysis software extensively used by phoneticians and others in related fields. Included is a syntax testing document which tests most cases using the recently updated new syntax and the old-style syhntax (now called "shorthand").

The syntax highlighting is the only thing included in this branch, but maybe in the future this can be extended.