driver: disable dataflow.max_discard if synchronized

during a synchronised acquisition, the client probably needs all the data, so don't discard anything

Note: this might not be the nicest way to do it. We might want to just allow the user to enforce/disable it.
gui: Enabled scroll wheel zooming when ROI tool is active
gui: Created auto-spectrum button
gui: Re-added Stream test frame (it got lost somewhere along the way)
gui: Made stream test cases compatible with the current stream implementation
gui: add clear() to stream controller

allows to remove all current streams. Will be used by the acquisition

also refactor by introducing more clear functions for the scheduler
gui: fix spectrum display

compute correctly the min/max of the spectrum bandwidth
fix .max .min on DataArray
gui: start the switch to analysis tab after acquisition
Merge branch 'master' of vpn.delmic.com:odemis