Add a couple of new options, begin python3 support
Echo error when no python support is enabled
Remove unused Error amd Warning functions
Unlet virtualenv_loaded when there is no python support, clean virtualenv_directory path, add virtualenv_python_scrip option
Finalize option names, minor cleanups
Refactor autoload/virtualenv.vim
Add virtualenv.py file
Do no import vim variables but pass them as arguments, minor cleanups