GLMixer Code

Small change of behavior in Mixing and Geometry views: dragging the
circle / frame is now possible only with the mouse action for panning:
otherwise it was too often moved by inadvertance.

Added new texture masks, and completely changed the process to create
and add masks: now a dynamic map of mask descritors and texture indices.

Intermediate, separation of init, picking and start capture into methods

Intermediate, separation of init, picking and start capture into methods

Intermediate, some blackmagic cleanup

Intermediate still: some blckmagic device querying done.

Intermediate. Blackmagic use no longer crashes, but you can only allocate it once

Intermediate. deallocating no longre crashed but reallocating then does

Committing smaller changes, before fixing Blackmagic camera de-allocation crash

Cleanup code (patch from Preeteesh)