TODO-timeseries.txt

events: partitioned timeseries for measurements, sqltags for the nonmeasurement events
  event from sqltags, find closest measurements of interest
standardise the sqltags for events metadata
events partitioned timeseries
events timeseries with timestamp/value pairs
typed memoryviews for mmap mode?
ts.setitems: use poke?
ts.setitems: prepad to max(when)
classes to accept int/float as an alternative to array typecodes
TimeSeriesDataDir: put the column mapping into the config.ini ?
TimeSeriesFile: open modes: basic read/modify/save, open for r or rw, mmap ro or rw
MultiTimeSeries: convenience add_rate(ratekey,accumulation_key) wrapper for add_derived, should backtrack to most recent non-NaN
MultiTimeSeries: add_derivation_rule(fnglob,infer(key)->(derived_key,derived_func(mts,when)) which calls add_derived
MultiTimeSeries: add_derived(key,func(mts,when)) to make a derives time series with func as a computation
MultiTimeSeries__getitem__: if no subdir, look for fnmatch based rule to make derived timeseries
MultiTimeSeries base class to provide __getitem[tskey] etc for TimeSeriesDataDir
MultiTimeSeries base class to provide __getitem[tskey] etc for TimeSeriesDataDir
TimeSeries: support slicing and indexed slicing