Save xfce4-terminal configuration (mostly for colors)

Just set XDG_CONFIG_HOME=$HOME/run_control/xdg_config
and changes to the gui config will save to this file.
Clean up prompt generation with a function
Massively simplify prompt definition with args
Remove imagemagick (last /opt) from PATH

I didn't need it for anything and it was throwing errors.
This keeps the PATH shorter.
Tweak terminal colors for differentiation/readability

again.