Fix error causing 3D plots to hang
Merge pull request #940 from UV-CDAT/vcs3D-fix_3d_plot_hanging

Fix error causing 3D plots to hang
Merge branch 'master' into vtk_ui

Conflicts:
	Packages/vcs/Lib/VTKPlots.py
Fixed a merge issue; logo was moved out of vtk backend
Added a contextual toolbar to fillarea

Allows editing of color and fill style, though that appears to not work
properly currently.
Refactor of click/drag logic

Extracted click/drag logic into mixin classes. Other editors will be
able to use the exact same logic, woohoo. Interacting with a toolbar is
still a bit fiddly, and there's tons of flashing; what's that all about?
Merge branch 'vtk_ui' of github.com:chaosphere2112/uvcdat into vtk_ui