Adds graph display systems to Skada. Uses Cryect's excellent LibGraph-2.0. To use these, create a new window in Skada. While doing so, choose one of the new display systems instead of the built-in bar display. Both use the normal Skada way of navigating, but also have buttons for it. Scrolling is also done the Skada way (mousewheel).
Currently there are two new display systems:
Historic line display is roughly equivalent to the realtime graphs in Recount. No permanent additional data is stored, only transiently while displaying.
Pie display is a simple pie chart.
There is no configuration as of now, and probably various other shortcomings.