fixed color keyword in time series plot - issue
Fix 33bb84b was to series.plot not timeseries.plot. This is the same fix for timeseries.plot.
Not sure why the def _maybe_add_color(kwargs, style, i) occurs in both _make_plot and _make_ts_plot?
#1890

`_maybe_add_color` :  they shouldn't be <i>defined</i> in both
 oops, left a comment to myself in the code
