Scene Debug: Tweaks and fixes

Cycles Shader Nodes List:
- Display amount of users and specify [F] if fake.

Also: List Lamps on Cycles
- Display Name of the lamp, Shadow Casting status, size, and samples (if Branched Path Tracing). Also display icon if active.

This are the very beginnings of the feature, handy at the moment but can get messy if there aremany lamps. Just committing what I have so far to keep it safe on the cloud.