Blender Git Loki

Armature: Add a special Pass for bone axes.

In object mode, the axes are drawn like any other wire objects with
depth test and depth write. Thus enabling MSAA to work but not their xray
behaviour.

In edit armature/pose mode, draw smooth line without depth testing. This
produces wrong draw ordering problem but still gives the desired xray
behaviour. We do it outside of the MSAA pass since the xray behaviour is not
compatible with it. But we are drawing smoothed lines so no need for MSAA.
The lines are 2px thick and improve readability.