Better Error Checking of PSF Files

[LSchwiebert]

Is your feature request related to a problem? Please describe.

GOMC currently does not check that the PSF file contains all the required dihedrals. This results in a segfault if a needed dihedral has been omitted.

Describe the solution you'd like

The code should check, based on the moves, which dihedrals are needed. If any are missing, it should generate an appropriate error message and exit.

Describe alternatives you've considered

None. But the current behavior is clearly not user-friendly, as a segfault provides minimal information on the cause.

Additional context

N/A

[LSchwiebert]

Note: This is related to issue #404, so it could be closed as a duplicate.