ORCA: add CASSCF relaxed scan

[berquist]

From cclib/cclib#1577

Also adds, for each ORCA program version, CASSCF calculations with and without symmetry on the beryllium atom. Beryllium is a good example because the ground state should be ~90% the closed shell configuration ($\mathrm{1s^22s^2}$) and ~3.333...% each of the doubly-excited configurations into the degenerate p orbitals ($\mathrm{1s^22p_{x}^2}$, $\mathrm{1s^22p_{y}^2}$, and $\mathrm{1s^22p_{z}^2}$), which looks like

---------------------------------------------
CAS-SCF STATES FOR BLOCK  0 MULT= 1 IRREP= Ag NROOTS= 1
---------------------------------------------

ROOT   0:  E=     -14.6164970082 Eh
      0.90188 [     0]: 2000
      0.03271 [     1]: 0200
      0.03271 [     3]: 0002
      0.03271 [     2]: 0020

This could probably become a standard unit test in the future.

[berquist]

This needs to be merged before cclib/cclib#1592.