COPYING: Update copyrights

I went through all of the protocols and used the copyright hints in
them and used the result of that to put in the COPYING file. One
exception was the fullscreen shell which was missing the copyright
details. As per direct contact with the original author, copyright of
fullscreen shell should be attributed to the author himself and was
therefore added to COPYING.

Signed-off-by: Jonas Ådahl <jadahl@gmail.com>