Blender Git Loki

Fix T43803: Crash playing smoke animation, when linked as group instance

The issue was caused by missing relations between smoke domain and flow/source
objects. This happened because smoke's modifier only iterated base objects and
ignored cases when flow/source could be linked to scene via dupli-group and
does not have real base.

The same seems to be still needed for fluid and dynamic paint modifiers,
will do it as a separate commit.

Reviewers: campbellbarton

Differential Revision: https://developer.blender.org/D1172