Added support for signalling system no. 5.

Added support for signalling system no. 5.

More infos will follow on the isdn4linux mailing list.

	modified:   Makefile.am
	modified:   Makefile.in
	modified:   README
	modified:   apppbx.cpp
	modified:   configure
	modified:   configure.ac
	modified:   default/options.conf
	modified:   dss1.cpp
	modified:   ie.cpp
	modified:   interface.c
	modified:   interface.h
	modified:   lcradmin.c
	modified:   lcrsocket.h
	modified:   mISDN.cpp
	modified:   mISDN.h
	modified:   main.c
	modified:   main.h
	modified:   port.h
	modified:   socket_server.c
	new file:   ss5.cpp
	new file:   ss5.h
	new file:   ss5_decode.c
	new file:   ss5_decode.h
	new file:   ss5_encode.c
	new file:   ss5_encode.h