BGE: Fix for [#32218] "logic.addScene() Not Adding Scenes in Order" reported by Josiah Lane (solarlune).

Adding scenes now uses a vector instead of a set to maintain order. This fix is partly based off of patch #32297 by Pavel Sadikov (sigmat).

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@57536 954f8c5b-7b00-dc11-b283-0030488c597c