IPAddress - Ethernet library compatibility fixes

Author: JAndrassy

api/IPAddress.cpp

@@ -116,4 +116,4 @@ size_t IPAddress::printTo(Print& p) const
     return n;
 }
 
-const IPAddress INADDR_NONE(0,0,0,0);
+const IPAddress arduino::INADDR_NONE(0,0,0,0);

api/IPAddress.h

@@ -23,6 +23,11 @@
 #include "Printable.h"
 #include "String.h"
 
+// forward declartions of global name space friend classes
+class EthernetClass;
+class DhcpClass;
+class DNSClient;
+
 namespace arduino {
 
 // A class to make it easier to handle and pass around IP addresses
@@ -67,12 +72,13 @@ class IPAddress : public Printable {
 
     virtual size_t printTo(Print& p) const;
 
-    friend class EthernetClass;
     friend class UDP;
     friend class Client;
     friend class Server;
-    friend class DhcpClass;
-    friend class DNSClient;
+    
+    friend ::EthernetClass;
+    friend ::DhcpClass;
+    friend ::DNSClient;
 };
 
 extern const IPAddress INADDR_NONE;