Add fish shell template

[mysy00]

Add #384
Looks like @ForgottenUmbrella didn't make any PR (or I missed it, sorry then). I slightly edited his colors to make them easier to read. Well, at least on the wallpapers I've tested.

To make it work go to ~/.config/fish/config.fish and add:

if test -e ~/.cache/wal/colors.fish
    source ~/.cache/wal/colors.fish
end

[snorkysnark]

It's better to use universal variables, like
set -U fish_color_command {color1.strip},
and then execute the file.

This way it reloads the colors in existing fish instances

[golam71]

ayo people why is this not getting merged?