Fixed ofxTCPServer being thread-unsafe.

The accept-thread would access deleted TCPConnections if the connection
closed. When the socket closes, accept() errors (socket is no longer
valid) then writes to the deleted TCP connection.
https://github.com/openframeworks/openFrameworks/issues/1901
fixed Thread-safe-fix causing socket to be closed in thread after being accepted

After copying the new accepted socket, the temporary would destruct and
silently close the socket. The next use (eg. recv) would return NOTSOCK
and kick off the client.
Ownership from the temporary is now explicitly taken. Not the best
implementation of ownership transferral due to the artictechture of
TCPManager
Merge branch 'develop-pullrequest' of github.com:SoylentGraham/openFrameworks into bugfix-ofxTCPServer
ofxNetwork: make copy private, copying these classes will destroy the connection
Removed superfluous comment
Merge pull request #1903 from SoylentGraham/develop-pullrequest

Fixed ofxTSCPServer being thread-unsafe