Well path models can now be added to geo mech models. Moved code that
adds well path models to a scene from RimEclipseView to
RimView::addWellPathsToScene(). This new function is now used by both
RimEclipseView and RimGeoMechView. Made sure that it is not needed to
load a result before well paths appear. TODO: Compute characteristic hex
element size for geo mech models.