Time Agg Series Slot Config: Skip intervals containing NaNs [6036]
Bug Number: 6036, preparation
Release notes (y/n): Maybe
For Release Nums: 7.2

Commit to development branch: Bug6036.

The "Skip intervals containing NaNs" option for Time Aggregation Series 
Slots was provisionally added.  With this turned on, when a NaN is 
encountered in the input series, the corresponding aggregated value is 
forced to "NaN".  This is demonstrated with this two-frame animated GIF:

  http://cadswes2.colorado.edu/~philw/2017/bugs/6036/TimeAggSerSlot-SkipIntvNan.gif

Note regarding Gnats 6036: Time Aggregation Series Slots are used 
ephemerally for time aggregation algorithms of other RiverWare features.
This includes the SlotTimeAggConfigDlg, used when changing the model's 
timestep size.  A static utility method in that dialog is, in turn, used 
by the "Set Run Timestep" script action.  The proposed solution to Gnats 
6036 is adding this "Skip intervals containing NaNs" capability to that 
script action's optional "Synchronize Objects with New Timestep" function.

Technical:

New members in class SeriesSlot::TimeAggSpec:

  bool _timeAggSkipNanIntv; // skip intervals containing a NaN
  void setTimeAggSkipNanIntv (bool skipNanIntv, bool notify=true);
  bool timeAggSkipNanIntv() const { return _timeAggSkipNanIntv; }

See also changes in Sim/SeriesSlot.TimeAgg.cpp.