In Ops and atan2 for nts, stop if no matching timetags in arguments.
in dat.h2o, pass avg to dat calls
Renamed other.dat.func to other_dat_func. Not longer exported.
We'll see if was necessary to be exported.

In average() more bug fixes related to weights.

Use exists and get instead of existsFunction and getFunction when
searching for a derived function.
Added some weight checking for averaging 3rd moments.
Removed avg,smooth parameter from dat.h2o.
help updates