Add capability to choose camera resolution

[soonum]

Currently the input camera image resolution is fixed and hardcoded (for 720p). This is definitely not a good thing. Indeed, one might use a camera working only in 480p, in that case selecting this camera as input source would cause HUBAngl to freeze.

This development will integrate two sub-features:

• automatic recognition of the preferred resolution for any camera (for video display initialization)
• ability to select an image resolution among a set of predefined ones (like 240,480,720,1080p) in the GUI.

For resolution selection by user, it would fallback on a supported resolution if the one selected is not suitable for the camera.