Audio buffer for writing / audio file sample data access

[hevonen]

It would be useful to have something like:

• extended audiofile so that it could be generated instead of read from file
• extended audiofile to allow read/write access to sample data
• audio ring buffer for writing raw pcm data, this would then be mixed with other audio sources

I think this would better mimic the way Processing allows access to pixels and screen buffer. In addition it would allow experimentation/prototyping with audio/dsp.