Allow users to disable the use of Powerline.

While I think it's a great default, it may not be for everyone.  So
provide a way for users to opt-out of having it, if they prefer the
default status line.

I updated my configuration as well, since I like being able to debug
things without Powerline in the mix.
Replace EnhancedCommentify with tcomment.
Merge branch 'allow-disabling-powerline' into mine
Merge branch 'replace-enhancedcommentify-with-tcomment' into mine

Conflicts:
	doc/notes.txt
	doc/tags