On CMake v3.28+, `EXCLUDE_FROM_ALL` is supported natively as an argument
to `FetchContent_Declare`.
On CMake v3.30+, `FetchContent_Populate`, which we use to polyfill
`EXCLUDE_FROM_ALL` support for older versions of CMake, is deprecated
and triggers a noisy warning.
Avoids the warning by using the native `EXCLUDE_FROM_ALL` support on
CMake v3.28+.
1. Platform and toolchain files are now all under `platforms/`, with a
single `CMake/platforms/${platform}.cmake` per platform.
2. Custom functions/macros are under `functions/`.
3. Finder modules are in `/finders`.
SDL_mixer can only stream a single music track
SDL_audiolib has unlimited streams.
With this change, we finally have streaming sounds (respecting
sfx_STREAM).
Audio options can now also be set via diablo.ini, which should help us
better diagnose the static noise issues.
Gleb Mazovetskiy
Sandro
staphen