===
Issue 14:
* ``svg.charts.plot.Plot``
(and hence its subclass ``svg.charts.time_series.Plot``)
now accept data as a sequence of pairs. Example::
import svg.charts.plot
g = svg.charts.plot.Plot()
g.add_data(dict(title='Example',
data=[(1, 1), (2, 4), (3, 9)]))
* data point labels that are drawn when
``show_data_values = True`` can have their label changed
from the default (which is the y-value) by giving a data item
a ``.text`` attribute.
It is convenient to used ``namedtuple()`` for this::
import svg.charts.plot
from collections import namedtuple
Datum = nametuple("Datum", 'x y text')
g = svg.charts.plot.Plot()
g.add_data(dict(title='Example',
data=[Datum(1, 1, 'first'),
Datum(2, 4, 'second'),
Datum(3, 9, 'third')]))
(in fact data items can have any extra attribute;
only ``.text`` is used currently)