Blender Git Loki

Fix for crash caused by effectors doing precalculation //during// DAG
updates.

This file crashes on loading with NULL pointer access to curve_cache:
{F77132}

The pdInitEffectors function was amalgamating the simple
collection of effector objects with an automatic precalculation for
curve guides and the like. This precalculation requires object data
that may not be available until the DAG has finished.

Since for DAG dependencies only the list of effectors is required,
added an argument to disable precalculation when collecting effectors.