Add DefaultMatrixAutoUpdate to Object3D

Cloning cleanup

Fix install instructions of Blender export on Mac. fixes #6994

Fix install instructions of blender export on a mac to what works and is recommended now. fixes #6994

Further improvements to the process are possible too (provide zip or make blender support installing py packages from dirs and not only zips, see issue for details)

For performance, I end up setting matrixAutoUpdate to false for the majority of objects and manually trigger the update as needed. It would be great if this could be set this way globally.

Somehow this became lost in the refactor

Fixing issues introduced in pull request #6953