Fixed typo in visualization documentation, moved error bar announcements from v0.13.0 to v0.14.0
remove trailing spaces, avoid using del on dataframe to remove a column
getting rid of duplicated code, loop over x and y error fields to get error bar series
effort to reduce code duplication, call _parse_errorbars in MPLPlot.__init__ instead of in _make_plot for specific plot type
added code to break out the error keywords from a dataframe before passing to plot_series(), when user has provided y keyword argument to df.plot()
_get_plot_function no longer returns plotf_name, use plotf.func_name() instead. reworked _make_ts_plot to comply with earlier edits to errorbar code
fixed bug in timeseries errorbar plot code
added errorbar tests when column names are ints