Add ability to add global palette offset for objects

[flamewing]

Some objects (example: Rexon badnik in Hill Top Zone in Sonic 2) use the foreground or background palette lines (lines 2/3). These palette offsets are coded into the game, so that directly loading the mappings with the level palette will be unable to display them with the correct colors. It can be worked around by splitting the palette lines, or by editing the game to use palette line 0 and bake the palette into the lines, but having the ability to add a palette offset for all frames of a given object would make things simpler.

[Brainulator9]

I agree, just for the fact that SonMapEd has this feature.