Modify ScopeDisplay so names of unused channels are still displayed.

The name of the channel is now displayed next to the gray box with
white X, to help users identify channels.  Positioning of channel
name (both when used and unused) was slightly modified to accomodate
change.
Modify ScopeDisplay.pas to improve usability in View Scans window

In the View Scans window, the fluorescence channel would display
with the top control button obscured, and much white space at the
bottom.  Rearranged spacing of ScopeDisplay components to try to
address this.
Modify spacing in ScopeDisplay

The spacing between buttons for channels not in use seemed too large;
after eliminating that, there were further spacing issues (x axis was
no longer visible in ADC channels display, while correcting that would
make the fluoro display lose its top resize button again).  This seems
to have fixed those.