Separate sprite rendering from specific actor behavior.
Use consistent naming for Images/Sequences.
Only show muzzle flashes for the active barrel.
Don't require an explicit animation key.
TODO: Make RenderSprites.anims private.

Things left to fix:
- Editor doesn't compile
- Fix Muzzleflashes across armaments
Move default animation state into RenderSimple.
Fixup: RenderBuildingRefinery.
Fixup: RenderUnitGunboat.