Add SDL_Mixer

[harry-cpp]

Adds SDL_Mixer and it's dependencies (MonoGame.Framework.dll.config will get moved in my PR to a proper directory...).

@dellis1972 @mrhelmut Can one of you provide me with SDL_Mixer.dylib for Mac, that's the only lib I am missing :/

[KonajuGames]

Having the .0 and .3 on the end of the .so filenames implies there should be symlinks somewhere to link the .so filename to the .so.0 and .so.3. I thought that was the "proper" Linux way these numeric suffixes worked?

Also, what does this give us that NVorbis and OggStream don't? What issue are we fixing with this?

[harry-cpp]

Having the .0 and .3 on the end of the .so filenames implies there should be symlinks somewhere to link the .so filename to the .so.0 and .so.3. I thought that was the "proper" Linux way these numeric suffixes worked?

Linux versioning is as follows:

• libSDL2_mixer-2.0.so.0.0.1 - the actual library
• libSDL2_mixer-2.0.so.0 - symlink, used for compatibility to describe that no API breakage has occured, if API breaks this symlink version will change its number to the new API version
• libSDL2_mixer.so - symlink, sometimes exists, always on Arch Linux, never on Ubuntu

In general you will want to use the second filename.

Also, what does this give us that NVorbis and OggStream don't? What issue are we fixing with this?

Join the party: https://github.com/MonoGame/MonoGame/issues/5562