Feature: colorize vertical lines - improvements

[lordfanger]

• When colorize vertical lines is enabled, whole file is always parsed to find end (and colors) for shown vertical lines. No parsing is needed anymore when scrolling, only after edits.
• VerticalAdornmentsColorizer has its own LayoutChanged event handler that recolorize vertical lines as soon as possible but it is still flickering lightly while scrolling/typing. I'm not sure if can be eliminated entirely.

[madskristensen]

Awesome. Thanks!!