zsh: add a color_bg function.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Move .zfunc to .zsh.

.zsh is the typical name for this directory, and there's really no good
reason to call it otherwise.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Merge branch 'master' into work