Blender Git Loki

Tweak ID->tag reset on file load (no visible change expected!).

Issue was, *some* IDs (like infamous nodetrees from materials etc.)
would not go through the 'main' read_libblock() func, so their tags were
never reset.

So now, we ensure direct_link_id() always clear the tags, and move
setting them in read_libblock() after the call to direct_link_id().

Needed for depsgraph, but general healthier fix actually.