Extract a function or class to step away from God Object.

See:

* https://en.wikipedia.org/wiki/God_object

* https://www.c-sharpcorner.com/article/god-object-a-code-smell/ .

This is Refactoring / code cleanup.

See:

* https://refactoring.com/catalog/extractMethod.html

* https://en.wikipedia.org/wiki/Code_refactoring

* https://www.refactoring.com/

* https://www.joelonsoftware.com/2002/01/23/rub-a-dub-dub/

Some small optimisations may have slipped in as well.

pysollib/game/__init__.py

@@ -465,6 +465,12 @@ class GameGlobalSaveInfo(NewStruct):
     comment = attr.ib(default="")
 
 
+# Needed for saving a game
+@attr.s
+class GameSaveInfo(NewStruct):
+    stack_caps = attr.ib(factory=list)
+
+
 class Game(object):
     # for self.gstats.updated
     U_PLAY = _GLOBAL_U_PLAY
@@ -710,9 +716,7 @@ class Game(object):
         self.demo = None
         self.solver = None
         self.hints = GameHints()
-        self.saveinfo = Struct(         # needed for saving a game
-            stack_caps=[],
-        )
+        self.saveinfo = GameSaveInfo()
         self.loadinfo = GameLoadInfo()
         self.snapshots = []
         self.failed_snapshots = []