A big cleanup operation.

* [SC] Triple arguments use the compound term rdf/3.
* [SC] Modules for agent types (ants, bees, entailers).
* [SC] Separate modules/folders for generic communication and navigation strategies.
* [SC] Various renamings, e.g. 'edge value' -> 'edge weight'.
* [DH_DYCLE,NEW] Added number_of_cycles/1.
* [DH_MESSAGES,NEW] New module for processing agent messages.
* [DH_NAVIGATE,NEW] Added number_of_steps/1.
* [DH_POPULATION,NEW] New module for population-wide predicates.