Add hex input to color selector for custom themes

[yskur413]

I believe that having the ability to simply enter a hex value (or set of RGB values) would make matching a theme's colors to its background image much simpler than using the graphical color selector that is available.

[sjain882]

Agreed. As a temporary workaround, however, one can export options, unzip, edit the theme files, re-zip, and re-import them.