Add possibility to define the background color of entities (black in ASCII, white in Unicode)

dungeonbattle/entities/monsters.py

@@ -1,9 +1,19 @@
+from random import choice
+
 from ..interfaces import FightingEntity, Map
 
 
 class Monster(FightingEntity):
     def act(self, m: Map) -> None:
-        pass
+        """
+        By default, a monster will move randomly where it is possible
+        And if a player is close to the monster, the monster run on the player.
+        """
+        # TODO If a player is close, move to the player
+        while True:
+            if choice([self.move_up, self.move_down,
+                      self.move_left, self.move_right])():
+                break
 
 
 class Hedgehog(Monster):