*  ninput.h :  extracted  duplicated  stream functions  from  a lot  of
 demuxers and do a nice (?) API.
 * stream.c: implement basic streams  manipulation. It is just a wrapper
 but it is useful.
 * all: added a i_ttl field in network_socket_t to allow per connection ttl
setting (in fact only used by access_out/udp.c.