#7 Visually outlining/highlighting nested blocks

[Armen Sarkissian]

Visually outlining and highlighting nested blocks for easier readability (see attached sample snapshots).

Please note the followings:
- The background gets darker as nested blocks get deeper.
- The same area (rectangle) is outlined/highlighted regardless of the positions of the curly braces.

[Armen Sarkissian]

sample outlined source code