Implement the Predator-Prey model

[frnsys]

The Predator-Prey (PP) model should consist of a few simple sub-models relating variables such as:

• humans
• animals
• etc

The relationships b/w variables should be parameterized too.

These variables and their relationships should be influenced by the monuments state (#5).

The PP state should have the format:

{
    'humans': 100,
    'animals': 200,
    'humans->animals': 2, # example relationship parameter 
    'animals->human': -1
}

[dantaeyoung]

The predator-prey model conceptualizes relationships between actors.

As noted in #8, the predator-prey model is computed from the state change of monuments. However, the model is run by the engine. AKA to use a Loopy metaphor: the model is the atemporal structure of relations between nodes/actors; the engine contains the update loop and makes everything run, and holds a temporal state.

The predator_prey engine is conceptually divided into four parts:

• [x] 1. (#22) monuments-to-relationships-logic (converts monument status to relationship model)
• [x] 2. (#23) relationship model (how actors relate to each other)
• [x] 3. (#24) world-state (actor status + relationships)
• [x] 4. (#25) pp engine (keeps everything running)

[dantaeyoung]

Currently working with commit d629d22.