color-theme-approximate

This package advises the `enable-theme' function and convert non-terminal colors
to their closest approximation. Inspired by VIM's CSApprox plugin
http://www.vim.org/scripts/script.php?script_id=2390

Normally Emacs does have non-terminal color themes degrade, however in some
system the effect is pretty poor. I've encountered this on Arch Linux and
Ubuntu (probably caused by some libvte weirdness).