Add universal audio player for ELSE

[timothyschoen]

• Download, compile and statically link ffmpeg for easier compilation
• Simplified code structure a little bit
• Put libsamplerate in shared folder, so circuit~ and ffplay~ can both use it

This is just a WIP version we can work on, here are some things we still need to do:

• For me, it currently crashes if I hit play with no audio file loaded
• The helpfile needs to be improved
• We might want to change the object name
• We might want to add the ability to load audio files to arrays directly (so you don't have to "record" into an array)
• I think the object's interface it nice, but you might have some ideas here ;)

[timothyschoen]

Maybe there could be an "array arrname" message to write the currently opened audio file to an array?

[timothyschoen]

Btw, this might not read all audio file types yet. I think I need to link some extra libraries like LAME and Vorbis too.

[porres]

I think we also need a new [soundfiler] object that can also import these files to arrays, and maybe save them too