Change CheckVarAction default to be != False instead of == True

Like most programs, we like a value to be "not false" instead of
"truthy".

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

agame/action.py

@@ -319,8 +319,8 @@ class CheckVarAction(Action):
     def __init__(
         self,
         var_id: str,
-        compare: Compare = Compare.EQUALS,
-        against: Any = True,
+        compare: Compare = Compare.NOT_EQUALS,
+        against: Any = False,
         yes: Union[Action, Sequence[Action]] = [],
         no: Union[Action, Sequence[Action]] = [],
     ):