Added an overpowered eagle boss. To avoid seing it too often, entities now have a certain chance of being spawned. Closes #19.

squirrelbattle/entities/monsters.py

@@ -100,3 +100,12 @@ class TeddyBear(Monster):
                  maxhealth: int = 50, *args, **kwargs) -> None:
         super().__init__(name=name, strength=strength,
                          maxhealth=maxhealth, *args, **kwargs)
+
+class GiantSeaEagle(Monster):
+    """
+    An eagle boss
+    """
+    def __init__(self, name: str = "eagle", strength: int = 1000,
+                 maxhealth: int = 5000, *args, **kwargs) -> None:
+        super().__init__(name=name, strength=strength,
+                         maxhealth=maxhealth, *args, **kwargs)