add options to have PyMolObserver only update on energy on conformation changes.
Options:
-update_pymol_on_energy_changes_only
-update_pymol_on_conformation_changes_only
These should be passed along with usual show_simulation_in_pymol option.
Note that by updating on energy changes only, pose length changes will not occasionally cause a segfault which sometimes happens when the observer kicks in and shouldn