Unsigned Sample Codecs and BitDepths

[wsc1]

The list of sample codecs has been paired down by one user's needs.

It is unclear if anyone out there needs or would want unsigned samples other than
byte.

It is also unclear if anyone would need more bit depths.

Note the sound interfaces use float64 to hold samples, and so there would be information loss
for storing 64bit int samples. I have not seen this in the wild, though.