Allow breaks in XYSeries plots

Some plotting libraries allow breaks to be placed in data plots by appending a point with NaN value.

For example a LineSeries showing angle data +-180. When the angle wraps from 180 to -180 a line series would currently draw a line through the x axis. You could append a NaN y value between the 180 and -180 point to prevent this connection being drawn.

Currently to achieve the same effect you have to use multiple line series which can be expensive if plotting large amounts of data dynamically.