Google 3D Tiles: Fetch tiles in background

[lassemt]

Currently Blender freezes when importing the most detailed tiles from Google Tiles API. This is expected since it is a heavy process. Can this be improved by running the task as a sub/multiprocess? Im not to familiar with Blender's API, but if it works it would enable us to work with other things in Blender while the tiles are loading.

[vvoovv]

@lassemt

It can't promise that your feature request will be implemented in the coming months.

A solution would be to start another instance of Blender while the first one is busy with the import of Google 3D Tiles.