Added .AU sound file format

We are noticed about some people needs support for .AU files on MACOS (or .SND files on NeXT or some *NIX systems). For this reason we added support for this file format.

Adding this format we have realized that the system of codecs could be improved, shortly we will update it.

Congratulations! Now we have another common audio file format for BrainWave and we will have an easiest audio codec system.