Orca: add optdone list, and populate with indexes when opts finish

* Once "FINAL ENERGY EVALUATION AT THE STATIONARY POINT" is printed,
  another single point at the new structure is performed. This is the
  structure that an index in optdone would point to.
Orca: remove assert statement related to finished optimizations

* Removed 'assert int(broken[2]) == len(self.atomcoords)'
* Assert statements "break" code, which seems undesirable. Better
  to handle the error gracefully and continue parsing file if
  possible.
Orca: adding example relaxed potential energy scan