.aliases: Add `chromekill` to kill all Chrome tabs to free up memory

Useful when you have a lot of tabs open (which I always do), but you don’t want to close them.

Tabs in Chrome are just processes, so we just filter out the ones we want, and kill them.

Closes #236.
.osx: `~/.CFUserTextEncoding` can break several Adobe apps

Ref. #237.
.gitconfig: Add comment about `color.ui` in Git ≥ 1.8.4

Ref. #239.