AudioStreamBuffered::onDefaultCallback() should call writeNow()

[philburk]

There is a FIXME in the code that needs to be reviewed. A unit test would help.

[dturner]

Phil to investigate independently

[philburk]

After analyzing the code, I think calling write() is correct. The readNow() zeros out the unfilled part of the buffer. There is no similar behavior for write. So there is now writeNow().

BTW, when studying the code I found Issue #233