fixed radius scale for spherical emitter

Seems like the scale should be applied to the radius before adding the base position.
fix random vector on sphere calculation

It seems that radius should be scaled before base position is added.
Merge pull request #6 from stemkoski/patch-1

fixed radius scale for spherical emitter
v0.5.0. Added auto-pooling on ShaderParticleGroup. Also added lots more comments to source code.
Merge branch 'master' of github.com:squarefeet/ShaderParticleEngine into gh-pages
Updated Pool example