Adding support for additional plot types. Now all variable types can be
plotted rather than just scalars as pseudocolor plots. A Combo near the
top of the VisIt Plot Viewer allows the user to set the plot type.

Removing the commented out code for the previous, play/pause, and next
actions that cycled through the elements in the list in the VisIt Plot
Viewer. This code was previously commented out in favor of the
TimeSliderWidget. This also required bit of minor refactoring.

Adding a missing copyright notice to the MOOSETreeCompositeView.

Signed-off-by: Taylor Patterson <pattersontc@ornl.gov>
Forgot to check the box to include this in my last commit.

Signed-off-by: Taylor Patterson <pattersontc@ornl.gov>