Lazy-load virtualenvwrapper
Lazy-load virtualenvwrapper

It seems the virtualenvwrapper initialization adds about 215ms to my
shell startup. In a test with 100 runs, lazy loading took the whole
shell startup about 398ms (error ~7ms), while the old startup took 613ms
(error ~15ms) - considering the only feature lost by lazy-loading is
completion on the first call of any virtualenvwrapper function, this is
a nice improvement.

TobiX/dotfiles,TobiX/dotfiles