BUG: remove old tree view from SceneViews

Removed the model and view files.
Updated the scene views logic to not use them.

Issue #1299
BUG: remove model and tree from CMakeLists

Don't build newly removed scene view tree and model files.

Issue #1299
ENH: remove white space, restore scroll

Clean up the html since not using an explicit style sheet, remove
extra white space.
Added saving and restoring the scroll position so user goes back
to the scene view node that they were previously viewing after
adding a new scene view.

Issue #1299