link shared parameters between multiviews

Now some of the paramters that change in one view, automatically make the same change in the other views. The potential set of parameters are those that are exact matches between all views. Of those we currently only implement time, phi and theta. Others are more problematic because the user might not want them linked, and because the implementation path to find and controll different widgets is not yet clear.

The new ParameterLinks instance holds the set of views to be linked and the set of parameters that should be connected and orchestrates the echoing of changes between the views.