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Refactor the g_Turtles array into g_Turtles and g_SpecialTurtles so that the special turtles aren't at the end of the array. This was done to make it easier to implement feature request #1542399, which is to remove the hard-coded limit on turtles. Keeping the special turtles in a separate array, rather than at the end of the g_Turtles array will make it easier to dynamically resize the array.