destroy more resources when emitter is destroyed (#1422)
destroy more resources when emitter is destroyed (#1422)

* destroy more textures, shaders, indexBuffer and material when emitter is destroyed
destroy all resources at the start of rebuild() too which overwrites them
MicroWorldwide/PlayCanvas,aidinabedi/playcanvas-engine,playcanvas/engine,MicroWorldwide/PlayCanvas,sereepap2029/playcanvas,playcanvas/engine,sereepap2029/playcanvas,aidinabedi/playcanvas-engine,sereepap2029/playcanvas