Remove "FPC" from variable names

[angelplasma]

As a rule we don't abbreviate the name of our organization nor endorse specific fan developed acronyms. These color names can just be that, I suggest find and replacing to simply remove the fpc- and use the color names as variables. So --yellow.

Originally posted by @bvhme in https://github.com/publiccodenet/publiccode.net/pull/143#discussion_r566710208