[evlatests] 20Hz changeover

[Jim Jackson]

Please hold off attempting to change from 19.2Hz to 20Hz timing in 
the EVLA.  After some confusion, we are now not certain how the 
current FPGA firmware in the DTS modules and the software running in 
the deformatters are going to react to that change. When asked 
before, the module designers assumed we were asking about the final 
(post 3-bit digitizer) versions of the firmware - not the current 
temporary 8-bit only DTS firmware. We are going to run some checks on 
a current module using the test racks before attempting it on the array.

Jim Jackson