Affectors now simulate with a minimum granularity

Affectors now simulate with a minimum granularity

Since all time is sourced from the ParticleSystem, the easiest way is
to alter the common time point while doing the multiple simulation runs.

Also removes the experimental TargetAffector.

Change-Id: Ieb52f8990445fe95f94070175a0f9beb6686324a
Reviewed-by: Martin Jones <martin.jones@nokia.com>