Finalising SubframeRefiner

Resolves #176 (closed), #159 (closed), #147 (closed), #136 (closed)

In this merge request I've added the final features to SubframeRefiner. The look of the pane is essentially finalised (I settled on two side-by-side tables showing the per-frame states before and after refinement.

1. Finalised layout of subframe.
2. Linked scrollbars of pre- and post-refinement tables
3. Made plot widget (bottom right) functional using QCustomPlot
4. Added widget to left panel to choose which parameters to plot in the plot widget.
5. Removed obsolete classes IntegrateDialog and RefinerDialog