Core: change how required versions work, deprecate IgnoreGame (#426)

`AutoWorld.World`s can set required_server_version and required_client_version properties. Drop `get_required_client_version()`.
`MultiServer` will set an absolute minimum client version based on its capability (protocol level).
`IgnoreVersion` tag is replaced by using `Tracker` or `TextOnly` with empty or null `game`.
Ignoring game will also ignore game's required_client_version (and fall back to server capability).

worlds/subnautica/__init__.py

@@ -28,6 +28,7 @@ class SubnauticaWorld(World):
     options = options
 
     data_version = 2
+    required_client_version = (0, 1, 9)
 
     def generate_basic(self):
         # Link regions
@@ -77,10 +78,6 @@ class SubnauticaWorld(World):
         item = lookup_name_to_item[name]
         return SubnauticaItem(name, item["progression"], item["id"], player=self.player)
 
-    def get_required_client_version(self) -> typing.Tuple[int, int, int]:
-        return max((0, 1, 9), super(SubnauticaWorld, self).get_required_client_version())
-
-
 def create_region(world: MultiWorld, player: int, name: str, locations=None, exits=None):
     ret = Region(name, None, name, player)
     ret.world = world