Possessed

* Fixed fire effect not showing when possessing an entity

* Fixed player keeping flight ability after stopped possessing flying creature

* Fixed wither skeletons not dealing wither damage

* Fixed some animations for skeletons, iron golems and polar bears

* Fixed snowmen not leaving snow trail when not in air

* Added creeper explosion ability

* Added skeleton infinite arrow ability

* Added wall climbing ability to spider

* Added ability for sheep to eat grass to regain wool

* Made shulker, wither and ender dragon unable to be possessed