Lazy-init the python code.

This is necessary to be able to run the python initialisation stuff when
the user has acutally done their settings: VimEnter triggers a call to
SunflowerFindTheSun, which checks if g:__sunflower_initialised is 1,
and if not, suns the initialisation code and then calls the
SunflowerFindTheSun function, setting the g:__sunflower_initialised to
0. Thus, we know for sure that we have run this code *after* Vim loaded
it's confuguration.