Also marked the existing functions as unsafe, as they can cause crashes if used in multi-threaded applications.
As a bonus, since the new functions are hashtable based, hint environment lookups are much faster.
SDL_Surface has been simplified and internal details are no longer in the public structure.
The `format` member of SDL_Surface is now an enumerated pixel format value. You can get the full details of the pixel format by calling `SDL_GetPixelFormatDetails(surface->format)`. You can get the palette associated with the surface by calling SDL_GetSurfacePalette(). You can get the clip rectangle by calling SDL_GetSurfaceClipRect().
SDL_PixelFormat has been renamed SDL_PixelFormatDetails and just describes the pixel format, it does not include a palette for indexed pixel types.
SDL_PixelFormatEnum has been renamed SDL_PixelFormat and is used instead of Uint32 for API functions that refer to pixel format by enumerated value.
SDL_MapRGB(), SDL_MapRGBA(), SDL_GetRGB(), and SDL_GetRGBA() take an optional palette parameter for indexed color lookups.
And SDL_IterateHashTableKey is only necessary for stackable hashtables, since
non-stackable ones can either iterate each unique key/value pair with
SDL_IterateHashTable, or get a specific key/value pair by using
SDL_FindInHashTable.
