[CGMZ] Scene Backgrounds - Version Alpha R3

Hi all, today this plugin was updated to version AlphaR3!
This update adds tint and opacity parameters to your backgrounds. These work for both scrolling and static backgrounds, so you no longer need to have multiple different tints of your background in case you want to use the same background image with a little color variation between scenes. This update also optimized the scene's ability to find the correct background if any exists.
- Added tint parameter for backgrounds
- Added opacity parameter for backgrounds
- Optimized background lookup code