Blender Git Loki

Cleanup: simplify order of initialization with argument parsing

Sub-systems that use directories from BKE_appdir needed to be
initialized after parsing '--env-system-datafiles'.

This meant the animation player needed to call IMB_init it's self.

Avoid this complication by having a pass that can be used to setup
the environment before Blender's resources are accessed.

This reverts the workaround from 9ea345d1cf82f