Modify View Line Scans interface to address timing issues

    The fluorescence and ratio channels would occasionally have timing issues
    with the ADC channels; in particular, clicking the half-range button would
    not let one go below a limit imposed by the window size (rather than by
    the minimum value attainable given the IDR file).
Merge pull request #10 from darrincedwards/viewscan_interface

    Modify View Line Scans interface to address timing issues