Merge branch 'master' into 'ladders'

# Conflicts:
#   squirrelbattle/game.py
#   squirrelbattle/interfaces.py
#   squirrelbattle/tests/game_test.py

squirrelbattle/enums.py

@@ -21,20 +21,20 @@ class DisplayActions(Enum):
 
 class GameMode(Enum):
     """
-    Game mode options
+    Game mode options.
     """
     MAINMENU = auto()
     PLAY = auto()
     SETTINGS = auto()
     INVENTORY = auto()
     STORE = auto()
+    CREDITS = auto()
 
 
 class KeyValues(Enum):
     """
-    Key values options used in the game
+    Key values options used in the game.
     """
-    MOUSE = auto()
     UP = auto()
     DOWN = auto()
     LEFT = auto()
@@ -52,7 +52,7 @@ class KeyValues(Enum):
     @staticmethod
     def translate_key(key: str, settings: Settings) -> Optional["KeyValues"]:
         """
-        Translate the raw string key into an enum value that we can use.
+        Translates the raw string key into an enum value that we can use.
         """
         if key in (settings.KEY_DOWN_SECONDARY,
                    settings.KEY_DOWN_PRIMARY):