ChargeableGraphics animations and LightningAttractor/LightningProperties additions

[radical_larry]

It would be really nice if chargeablegraphics would support animations for its default state, not just while charging/discharging. The animation transitions between charging and discharging could also be improved by letting us set a flag to not restart the animation on the first frame, but rather keep going where it stopped in its last state. Alternatively a setting to share one spritesheet for all three states (idle, charging, discharging) with different animation speeds for each state, whatever is easier to implement. Right now something like a wind turbine animation constantly jumps back to the first frame of the animation when it switches between charging and discharging, while idle animations are completely impossible.

For the lightningattractor, an array that contains the types of lightning it will accept as energy input would be great, as well as letting planets have multiple lightningproperties, if that's even possible in the engine.