Signal a recognizable NNTP EOF error instead of a simple error if the

Signal a recognizable NNTP EOF error instead of a simple error if the
the server silently closes the connection and NNTP-READ-LINE receives
an EOF, so that NNTP-PROTECT can handle the condition and reopen the
connection in this event, when before it would just signal an Edwin
Edwin error.  The response field of NNTP errors can now be either a
string or an EOF object.