osg::DisplaySettings class. OsgCameraGroup will now read the setting
from the DisplaySettings instead of hardcoding the value. I added the
following commandline option to be able to set the multisample value:
--samples <num>
One thing to note, OsgCameraGroup would previously check if the
computer is an SGI and set multisample to 4. I retained this check in
DisplaySettings to be backwards compatible."
