Private constructor called in TCPSocket accept, when creating a new Socket.
Close() method calls moved "up" to InternetSocket.
InternetSocket::close() returns proper error code when no socket available.
Add TcpSocket::accept icetea tests.
Deleting sockets moved to teardown.
Static Thread methods and signal methods have been deprecated. Remove
all references in the main code, and most of the tests. Some tests of
the deprecated APIs themselves remain.