[3D] Support switching to 3D resolutions

Include matching 3D flags (SBS/TAB) in the score of a resolution to switch to, to enable switching to 3d modes.
Also remove the old code that treated 3D modes differently when assigning a score.

This reinstates auto switching to 3D mode on the PI that was lost in the stereoscopic update.

Note: This is an RFC.
@elupus?
You have not addressed this it seems? How do you intend to handle the case of a system provided 3d mode where you must trust the pixelratio it provides?

For a full 1080+1080 3d mode we should not divide pixelratio with 2.0.