libmpg123 library version 1.29.0 (2021-09-06).
The following changes have been made:
- ports/MSVC++/config.h and ports/MSVC++/mpg123.h have been retained from older
  versions.
- ports/Xcode/config.h and ports/MSVC++/mpg123.h have been retained from older
  versions.
- ports/MSVC++/mpg123.h has been adjusted to provide mpg123_ssize_t and define
  MPG123_NO_LARGENAME.
- Modifications are marked by // OpenMPT.
- Obviously, unnecessary folders and files have been removed.
- For building, premake is used to generate Visual Studio project files.
  See ../build/premake/ for details.