Update base16-iterm2 submodule
Update base16-iterm2 submodule

Seeing as I updated the other base16-related submodules, I may as well
update this one too. Funnily enough, it hasn't been updated since the
great move.

* vendor/base16-iterm2 a2d664f...6930c26 (1):
  > Merge pull request #16 from alexbaumhoer/chore/update-readme

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