using sh syntax + temp virtualenv to avoid pip -t error
using sh syntax + temp virtualenv to avoid pip -t error + install argparse if needed
only load autocommands if g:vimfox_autocommands is defined by user
now creates an empty g:vimfox_autocommands if not declared by user.
g:vimfox_autocommands not instantiated in plugin/vimfox.vim
Merge branch 'dev'
'various fixes'