FEATURE: Subplots for the TSD graph display

[buggsley]

When displaying multiple plots for variables, they heavily overlap and
sometimes it makes user hard to identify them. It would be better if the
plot of each variable has its own window, like the matlab subplot function (
http://www.mathworks.com/access/helpdesk/help/techdoc/ref/subplot.html).

--
Zhen Zhang

[buggsley]

Can likely be done with a CombinedDomainXYPlot.