Blender Git Loki

Merge branch 'master' into temp-startup_blend

Fix T42032: Freestyle panel order

resolve for cycles & blender-internal

Update layout for motion tracker: T41660

As suggested by Sebastian König

tweaks for writing startup.blend

- always calloc
- don't write id-properties

this is to make sure addon settings aren't written by accident, any new data starts out zero'd (no junk bytes)