Vim config changes. * Disabled `interestingwords` for now because it messes up my `n` map. * Try to improve `supertab` settings. * Fix problems with `<c-[>` actually being `<Esc>` on US keyboards, wtf.

# Make the prefix easier to type, like 
# pretty much everybody on the fucking planet.
unbind C-b
set -g prefix C-a
bind C-a send-prefix