Augment Python Path with all "pylib" directories in Vim runtimepath.
Move sniputil.py to common pylib directory for easier sharing.

Add "setpypath.py" files into UltiSnips directories to avoid
duplicating sys.path logic for locating sniputil.py; update all
UltiSnips/*.snippets.py files to use setpypath.
Merge uses of betterVisual from John Szakmeister's pull request.

Request URL:  https://github.com/drmikehenry/vimfiles/pull/122
Record changes for Python sys.path augmentation.