Support Ogg Vorbis file format

[DanielSWolf]

For some developers, working with uncompressed WAVE files may not be an option. For instance, users of Visionaire Studio typically work with Ogg Vorbis files throughout development. Similarly, Spine supports .ogg files, but Rhubarb for Spine does not.

Rhubarb should support .ogg files (Ogg Vorbis) as an alternative to .wav files.

[DanielSWolf]

Implementation sketch: vorbisfile is a high-level API built on top of libogg and libvorbis with a compatible license. I skimmed the documentation, and it shouldn't be hard to implement the AudioClip interface. Then, instead of using WaveFileReader directly, I'd implement a builder function that analyzes the file name, then returns a smart pointer to either implementation.