Import 3D Scene Improvements
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

-If re-importing from the "dependency changed" dialog, edited scene will keep the local changes.
-Imported scene will keep track of changes in the source asset
-Geometry changes in source geometry or nodes with a different transform will be updated.
-Materials will be kept if changed locally.
-New nodes added will be kept
-If nodes were reparented or renamed, they will still keep track
-Deleted notes will be restored, use the -noimp option to avoid this.
-In general, you can trust that if you do local modifications to the imported scene, they will not be erased after re-import.
-Erasing your changes is done by re-importing from the "Re-Import" menu, re-opening the "Import 3D Scene" dialog. This wil re-import fresh.

Overall, This should allow you to work on a scene and see changes made to 3D assets in real-time.

So Please test!!
Merge remote-tracking branch 'upstream/master'