MjpegServer uses the timeout to generate keep-alives to any clients
(which helps detect disconnects and avoid stale client threads).
CvSink GrabFrame now defaults to a timeout, but the timeout can be
changed by the user, or the old no-timeout version is now available
as GrabFrameNoTimeout.
When the page is loaded, if properties can be found they will
automatically be created on screen. They are currently not auto
updating. Raw values are currently disabled because of this.
The code now automatically resizes as required.
This change also disconnects camera resolution settings from MJPEG
stream connections; setting the camera resolution can now only be done
via code.
