More precise type information for has_flag

[curiosity]

Right now the type of the parameter is listed as string whereas in fact it's one of the respective string literals (and the game will error if you try to pass any other string). This affects all instances of the method (including ghost_has_flag).

[Bilka]

Thanks for pointing this out, all has_flag and ghost_has_flag methods will have better types for the next version. The types of the Flags concepts have been split similarly to how CollisionMask and CollisionMaskLayer are separate types for the dictionary and the union of strings.