Automatically enable required add-ons in Blender preferences

[antoineruzette]

Users can simply run the setup_world function instead of manually enabling in the preferences the 'add_mesh_extra_objects' add-on during first installation. https://github.com/smegason/Goo/blob/3c6d8f5f85da776a22e385a88feba4d5b0e74b71/scripts/modules/goo/goo.py#L1887

If other add-ons become needed to run Goo, they will be added in future releases.

Thanks to Charles Dai for the idea.