Color configurability (special emphasis: colorblind support)

[narc0tiq]

Via http://www.factorioforums.com/forum/viewtopic.php?p=116831#p116831: a way to configure the specific colors used as the gradient stops (currently: green, yellow, red), as well as an option to force the gradient off (showing only the most applicable color of the three -- no blending).

Makes a really good first entry to the config GUIs.

[Protheus]

can you add an option to set font color as in below screenshot.. the top entry is hardly visible with my colorblindness

https://imgur.com/a/0JQ7gT3