Fixes code comment.

Signed-off-by: Jim Teeuwen <jimteeuwen@gmail.com>
Adds Device.PlayU16() method. This is a convenience method
to alow playing of a 16 bit PCM buffer. It casts the data to
a 8-bit buffer and calls Play(). This is done by using an
unsafe cast, to prevent the need for copying, reallication
or reflection magic.

Signed-off-by: Jim Teeuwen <jimteeuwen@gmail.com>