Added new options; this is to unify the available options so most of the options have *Start, *StartSpread, *Middle, *MiddleSpread, *End, *EndSpread.
Started to implement the new options.
Merge branch 'dev' into newOptions

Conflicts:
	src/ShaderParticleGroup.js
Fixed SPE.Group#colorize not working.
Fully tested new options. Ensured random values are > 0 where necessary.
Updated README for v0.7.3.