Removed duplicate hints SDL_HINT_APP_NAME, SDL_HINT_APP_ID, and
SDL_HINT_AUDIO_DEVICE_APP_NAME.
Wired up a few things to use the metadata; more to come!
Fixes https://github.com/libsdl-org/SDL/issues/4703
It was intended to make the API easier to use, but various automatic garbage collection all had flaws, and making the application periodically clean up temporary memory added cognitive load to using the API, and in many cases was it was difficult to restructure threaded code to handle this.
So, we're largely going back to the original system, where the API returns allocated results and you free them.
In addition, to solve the problems we originally wanted temporary memory for:
* Short strings with a finite count, like device names, get stored in a per-thread string pool.
* Events continue to use temporary memory internally, which is cleaned up on the next event processing cycle.
This was just causing confusion and anxiety. SDL temporary memory will be automatically freed on the main thread when processing events and on other threads when it ages out after a second. The application can free it directly by calling SDL_ClaimTemporaryMemory() to get ownership of the pointer, if necessary.
SDL_BlitSurfaceScaled() is more flexible and uses the SDL_SoftStretch() fast path when possible. Having two surface scaling APIs was confusing, especially when one of them has unexpected limitations.
This was originally to avoid duplicating clipping work in Maelstrom on a 486 computer. This has been confusing for users and computers are a little faster these days, so we'll make it work the way people expect.
The function can now convert between pixels of different formats, and takes a parameter to control whether the premultiplication is done in sRGB or linear space.
Also added SDL_PremultiplySurfaceAlpha(), which can premultiply the pixels of a surface in-place.
Applying these changes to external code doesn't actually improve anything, and within the context of the other Get* functions for renderers and surfaces, these stand out as outliers, so I'm going to back this change out.
