vim: don't blow up when launched as `vi`
vim: don't blow up when launched as `vi`

Plug-ins cause no end of trouble. Without them, Vim is more than happy
to run as `vi` without complaining.

wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent