TimeSeriesDict.plot: added instance method

    - for convenience only, tries to determine figure kwargs versus plot
      kwargs, probably needs more attention
Table.binned_event_rates: new 'name' for rates
docs/examples: added trigger rate docs and examples
HistogramPlot: set log axis if logbins=True
Table.hist: added instance method for histogram

    - takes a column and returns a HistogramPlot
examples: added example on table histograms