USAGE:
Select Objects individually, not Branch to mirror model, run script.
When done mirror modeling you may wish to Select all instanced objects when done and freeze to remove lattice ops and cut unparent from originals if nessessary, or delete them and reinstance the originals using another mirror method before use

If you wish to work away from the global center or moving the parent model null of the instanced objects meshes, well moves them away from each other relative to global world center, then parent the lattice to the parent model/null