WIP: Explosions

Originally done by @Shadmar for Paragon but back ported and some changes made.

Todo:
* pack all images onto a singe texture atlas (worthwhile?)
* load as many images as are available
* set playback rate / lifetime to match anim frames

Future work:
* spawn addition explosion particles from the vertices / surface of the collision mesh
* ???

Feedback welcome since this is a port.