Refactor duplicated code (from 0159e4f969)
Add line length guideline to code editors (from d9c1729a8f)
Allow turning off zero-padding for line numbers (from 00b3af246b)
(In 3.0 zero-padding is off by default, but for 2.1 I'm setting the default to be on because it's how it always worked.)
Fixed line lenght guideline drawing with color option (from @Paulb23's 6b42cd5fe6)
0dbfb864ad