neovim full color support

[mortenbh]

Instead of

if has("gui_running")
https://github.com/ciaranm/inkpot/blob/master/colors/inkpot.vim#L49

maybe consider something like

if has("gui_running") || &t_Co == 88 || &t_Co == 256
https://github.com/nanotech/jellybeans.vim/blob/master/colors/jellybeans.vim#L60

so that neovim in full color mode can use the GUI colors as well?

Thanks!