add dwell to SweepEntry
sweep fixes: pass trigger type properly, iterations infinite
factor out sweep setting update
don't call trigger directly any more
remove self.dut from MainPanel
close cleanly when not connected
move access to sweep list to single method
trig_set None -- no trigger
remove debug prints
continuous sweep mode
Merge branch 'sweep-device' into triggers-sweep-dev
added capture device, began implementing capture device into GUI