Hi, this reply might come late, but anyway ;-) you can unpack it since it's just a renamed ZIP-package...
Youe need to take several steps to add colors:
1) Inside the archive there is a file called "common.js" in which there's only one function called "updateColor" (when I was writing this post, of course ;-)) and there you find the "color schemes".
2) in Settings.html at lines 42-46 (should be in js function init()): for every added color scheme add a line "colorchoice.options(x).text = text[y]" where x should be the index of the html select-element's option child element (see lines 184-190)... the "y" comes next
3) in language.js add a line text[y] = "your-color-scheme-name" where the y must correspond to the y from step 2... (if you want to add the french translation, also do this for the language.js file in the fr-subdir... by that you can also add your own translation...)
4) inside Settings.html again, add the appropriate option child elements to the aforementioned select-element (lines 184-190) where only the "value" attribute must correspond to the name you used in the "common.js"-file!
Hope that helps to add your own color-scheme / language