Fixed loss of important patch/diff aspects and too aggressive diff coloring.

- Contextual diff lines (preceding/following lines of changed lines) are crucial, must not visually appear as unimportant, greyed-out content.
- Restore colorization of comments in added lines for readability and to encourage code comments.
- Generally decrease background color saturation to shift focus on code, instead of colors.
Merge branch 'diff-coloring' into sun