eljost/pysisyphus: Bugfixes & expanded documentation

Bugfixes

• Added missing files for worked example of trispericyclic reaction in examples/complex/08_trispericyclic/
• Initial displacement from TS using 3rd derivatives of the energy (displ: energy_cubic) should now be more reliable. The resulting HDF5 dump can be reused via the displ_third_h5: [path to hdf5] option (see the IRC documentation)

• Improved calculator documentation for ORCA, XTB, Turbomole and Calculators in general
• Added Citation.cff
• Updated Turbomole tests and added Turbomole Growing String examples using the native pysisyphus calculator as well as the QCEngine wrapper