Small bugfix which ensures that the Color variable in PolygonSprite is set all over, instead of querying the vertex colors. (Which can differ from the actual set color due to packing).
Also fixes bug where current color isn't used to set vertex color when setRegion is used. (As color wasn't being maintained)
Merge pull request #2478 from codepoke/bugfix-polygonsprite_color

Small bugfix with regards to PolygonSprite Color usage