gui: Connected the 2x2 view menu item
gui: linked the crosshair menu item to the currently foccussed so it can be toggled
gui: Changed SpotMarkerOverlay into a simpler SpotModeOverlay
gui lens align: fix conversion AB to XY

after we changed to the convention that Y is going up, this has to change too.
Merge branch 'master' of vpn.delmic.com:odemis