Add powerline_full theme
Add powerline_full theme

Add PYTHON_ENV_MARKER config option, defaults to "(e) ".
Change default POWERLINE_SPACER to the non-breaking space character, as
(according to the Powerline project) some fonts don't correctly respect
spaces otherwise. Any user using powerline has to have Unicode support,
so there should be no downside to this default.

Add a version of the powerline theme that includes all of the supported
data functions from the default theme, just in a powerline style.

laurentbardin/liquidprompt,milouse/liquidprompt,nojhan/liquidprompt,pkkolos/liquidprompt,jaesivsm/liquidprompt