[evlatests] Spectral Line fast dumping

[Rick Perley]

    The replacement of the system controller, and the departure of the 
modcomps, has removed the major bottlenecks for 'fast dumping' -- using 
short integration times -- for spectral line modes. 

    I ran a rest last night to see just how fast we could go.  The 
results are quite remarkable, and have exceeded Ken's predictions:

    With 256 total channels (in mode '4'), we lost no data at 3.33 
seconds integration. 
    With 512 total channels (in mode '2AC'), we lost not data at 5.0 
seconds integration. 

    We'll try even faster rates later today, when time becomes available.