Add support for parsing enum formats with comments containing the type.

For example:

typedef enum /*: NSInteger */ {
   GKGameCenterViewControllerStateDefault = -1,
   GKGameCenterViewControllerStateLeaderboards,
   GKGameCenterViewControllerStateAchievements,
   GKGameCenterViewControllerStateChallenges,
} GKGameCenterViewControllerState;