Cannot create a card colour without creating a tab in the card library

[Strikefinger]

Line 3 of ColorTabBarFix.Fields.Ctor.Postfix in ColorTabBarFix.java assumes that there is a library colour. However, if a tab in the card library is not desired (for example if it simply duplicates cards from an existing colour with a different background colour) one has to still create a library colour and then skip rendering of the tab button.

I assume the missing check if CardLibrary.LibraryType contains the colour is simply an oversight and not intentional, because there is no comment marking it as such.

I propose adding a check if the library colour does not exist, and in that case skipping the tab / continue with the loop.