I hate doing this but I am tired of touching a fish script as part of
some change and having `make style` radically change it. Which makes
editing fish scripts more painful than it needs to be. It is time to do
a wholesale reformatting of these scripts to conform to the documented
style as implemented by the `fish_indent` program.
This adds a special colorscheme and prompt function guaranteed to work
on a VT and activates them automatically if $TERM = "linux".
set_color is overridden to only allow the 8 colors VTs have (under the
assumption those are always the same) and the color variables are
shadowed with global ones so they don't pollute our nice capable terms.
