Pretty sure source/blender is now finished, with all legacy matrix calls confined to gpu_matrix.c.
This was the easy part, but doing it first makes the next part much easier. TODO and XXX notes describe what is left.
glMatrixMode is still in place, since the new API does not share this concept of modes. Similar for glOrtho and glFrustum which I'll tackle very soon.
Part of T49450
It also adds nice occluded silouhette information for selected objects that are behind visible objects.
This methods is really heavy because it needs to render the wires twices.
There are now only referenced in:
* drawobject.c
* particle_edit.c
* space_image.c (a single case to be handled on workspace branch)
* rigidbody_constraint.c (to be handled in the following commit)
