gui: inverse SPARC Pitch

from test on real hardware.
gui: Plotcanvas label update
gui: Focus label update
gui: Polar overlay intensity label update
gui canvas: cache the wxImage from Goal image

conversion is very costly, so cache it.
We need a general mechanism and put/hide it into canvas

Should help with performance issues on the sparc alignment tab with hires cameras
stream: Make OPTICAL_STREAMS more generic

basically, this add CameraNoLightStream to the optical stream.
Mostly helpful for the sparc alignment tab to get the right icon
Merge branch 'master' of vpn.delmic.com:odemis