Better set / update data logic
Many changes, see detailed list

- startStopEqual in AlignDescriptor
- fixing interval show on data
- markerPlotArgs in AppearanceSpec
- setPrimaryUnits for channels
- auto convert to scalar param if all scalar OR empty
- fixing repair data to use nans in that case
- fixing getCellElementClass to find first nonempty
- fixing autoOccupied to apply attribute filters and manual axis lists
  first
- adding TrialDataOnDemandCache to cache .valid
- improving addAnalog, addParam, addEvent logic
- adding typed addScalarParam, stringParam, booleanParam
- getParamRaw will return analog sample, warning if not aligned to
  single event so that analog only has 1 timepoint
- adding conditionsSize and nAxes pass thru on TDCA
- fixing getParamGrouped, adding getParamGroupMeans
- plotParamScatter, plotParamVsParamLine, plotParamVsParamCovariance
- making use of newplot in getRequestedPlotAxis