Dashed Line Option
Added a dashed line option to the graph.
This can be either one of the specified types in styles.css (which can be expanded as necessary).
OR
It can be a list representing the dash/space length as required.

For example, to use the 0th pre-set dash (even short dashes):
xy_chart.dashed_line=0
OR
for a new dash array
xy_chart.dashed_line=[1,2,3,4,5,6]
This create a dash of length 1, a gap of length 2, a dash of length 3, a gap of length 4, ...

This was already possible with manually specifying CSS (see: http://pygal.org/news/, config.css.append('inline: path { stroke-dasharray: 15, 5, 10, 5; } .guide { stroke: none !important }')), but this might be more user friendly.

This is intended for a later expansion of individual styles per line.
Individual Line Configuration
Updated dashed_line values so dashed_line=0 is a solid line
Added the ability to perform individual line configurations.
This controls the following settings:
show_dots, show_only_major_dots, dots_size, stroke, dashed_line, fill

To use this, add the LineConfig class, as with the Config class
Then use the 4th input to .add to specifice line config
The 3rd input to add is True if the second series, False otherwise

The LineConfig class populates any missing values with the defaults from Config

Example:
import pygal
from pygal import LineConfig
xy_chart = pygal.XY()
xy_chart.add('A', [(0, 0), (.1, .2), (.3, .1), (.5, 1), (.8, .6), (1, 1.08), (1.3, 1.1), (2, 3.23), (2.43, 2)],False, LineConfig(stroke=True,dashed_line=1,fill=True))
xy_chart.add('B', [(.1, .15), (.12, .23), (.4, .3), (.6, .4), (.75, .21), (.8, .3), (1, .8), (1.7, .8)],False, LineConfig(stroke=True,dashed_line=0))
xy_chart.add('C', [(.05, .01), (.13, .02), (1.5, 1.7), (1.52, 1.6), (1.8, 1.63), (2.1, 2.23), (2.3, 1.98)])
xy_chart.fill=False
xy_chart.dashed_line=[1,2,3,4,5,6]