Blender Git Loki

Fix T49827L Crash linking material while in Material viewport shading mode

Material linking might and does change the way how drawObject is calculated
but does not tag drawObject for recalculation in any way.

Now use dependency graph to tag draw object for reclaculation. Currently do
this using OB_RECALC_DATA taq since tagging is not very granular yet. In the
future we can introduce ore granular tagging in the new dependency graph
easily.

Simple and safe for 2.78a.