[DMMAT additions] Once Add/Edit DMMAT working, work on these

[janineA]

After #9 :

Sensor menu

• Add/Edit Sensor -> Add master sample rate?
• A2D card sample rate -> Code the DIAMOND card the same? Talk to Josh
• Generate filter based on sample rate. Set one sample rate for the card and one for the sample. (variable subsampling)
  -- Numpts = card rate/sample rate
  -- Only use boxcar for now.
  -- Talk to Josh
• Add a field to enter latency. Assume latency is always 0.25, so have it there, but greyed out.
• Save a sensor without a cal file. Have code create a basic cal file with 0,1,0 as cals.

Variable menu

• Add ability to add/edit sensor, sample and variable parameters.
• Modify Add/Edit DMMAT so gain and bipolar are the same for all channels
• Have user enter once, then replicate under all vars for that sensor.