proper fix to EC_ParticleSystem refactor: was a typo, changing 'AttibutesChanged' to 'AttributesChanged' fixed it.

is unfortunate that it compiles with such typos. there seems to be discussion how c++ doesn't currently have a crossplat solution to this, http://stackoverflow.com/questions/497630/safely-override-c-virtual-functions
Merge pull request #610 from antont/particlesfix

proper fix to EC_ParticleSystem refactor: was a typo, changing 'AttibutesChanged' to 'AttributesChanged' fixed it.