Added a new class StripToolPlot--it's supposed to manage all of the plot and pv series info.
Added two new classes--StripToolPVListModel and StripToolSeries. The list model seemed like a good idea because it could take care of manipulating the qstandarditemmodel sort of away from the view, which is in StripTool. I created StripToolSeries because it seemed like an easy way to make units a property of the selected plot series, so they can be displayed on the plot
The units now display on the plot when the plot is selected (if they have been included when the pv is first added).
Merge branch 'master' of https://github.com/acquaman/acquaman
Re-implemented the show/hide feature for the plot.
The pv name now appears on the plot when a particular line is selected.