Rename multiple getFitness functions to more specific names
Renamed 3 getFitness functions to more explicit variants:
- IndividualLocationPerception: getFitness --> getIndividualFitness
- Organisation: getFitness --> getOrganisationalFitness
- MultiplexLandscape: getFitness --> getLandscapeFitness
This makes the code better readable and more explicit which fitness function is being called.
These changes were tested by running both the pytest tests and the main.py module.