introduce the ns3::String class, get rid of the string -> Attribute implicit conversion, and get rid of MakeDataRate, port PointToPointNetDevice to Attributes

src/node/ipv4-address.cc

@@ -305,14 +305,14 @@ std::istream & operator >> (std::istream &is, Ipv4Address &address)
 {
   std::string str;
   is >> str;
-  address = Ipv4Address (str);
+  address = Ipv4Address (str.c_str ());
   return is;
 }
 std::istream & operator >> (std::istream &is, Ipv4Mask &mask)
 {
   std::string str;
   is >> str;
-  mask = Ipv4Mask (str);
+  mask = Ipv4Mask (str.c_str ());
   return is;
 }