refactored zoomExtents
refactored zoomExtents

this function needs to be outside of the UI object in embed scenarios
with no UI.  Next step - clean up layers and views.

tt-acm/Spectacles.WebViewer,bhowes-tt/vA3C_OBJviewer,bhowes-tt/vA3C_OBJviewer,tt-acm/Spectacles.WebViewer