Big refactor v0.30

All test pass, except for the TestConfig suite, which is not too critical as the
plan for this version onwards is to avoid configuration as much as possible.

examples/custom_timeouts/custom_timeouts_sim.py

@@ -4,8 +4,7 @@ from soil.time import Delta
 
 class Fibonacci(FSM):
     """Agent that only executes in t_steps that are Fibonacci numbers"""
-
-    defaults = {"prev": 1}
+    prev = 1
 
     @default_state
     @state
@@ -25,23 +24,18 @@ class Odds(FSM):
         return None, Delta(1 + self.now % 2)
 
 
-from soil import Simulation
+from soil import Environment, Simulation
+from networkx import complete_graph
 
-simulation = Simulation(
-    model_params={
-        'agents':[
-            {'agent_class': Fibonacci, 'node_id': 0},
-            {'agent_class': Odds, 'node_id': 1}
-        ],
-        'topology': {
-            'params': {
-                'generator': 'complete_graph',
-                'n': 2
-            }
-        },
-    },
-    max_time=100,
-)
+
+class TimeoutsEnv(Environment):
+    def init(self):
+        self.init_network(generator=complete_graph, n=2)
+        self.add_agent(agent_class=Fibonacci, node_id=0)
+        self.add_agent(agent_class=Odds, node_id=1)
+
+
+sim = Simulation(model=TimeoutsEnv, max_steps=10, interval=1)
 
 if __name__ == "__main__":
-    simulation.run(dry_run=True)
+    sim.run(dry_run=True)