Cleanup code using forward declarations.

Use misc methods of avoiding unnecesary header includes.
Replace int typedefs with int##_t from stdint.h.
Replace PRI64[xdu] with PRI[xdu]64 from inttypes.h.
Normalize QT_VERSION ifs where possible.
Resolve some indirect dependencies as direct ones.
Remove extern declarations from .cpp files.

src/protocol.h

@@ -11,11 +11,13 @@
 #define __INCLUDED_PROTOCOL_H__
 
 #include "chainparams.h"
-#include "serialize.h"
 #include "netbase.h"
-#include <string>
+#include "serialize.h"
 #include "uint256.h"
 
+#include <stdint.h>
+#include <string>
+
 /** Message header.
  * (4) message start.
  * (12) command.
@@ -67,7 +69,7 @@ class CAddress : public CService
 {
     public:
         CAddress();
-        explicit CAddress(CService ipIn, uint64 nServicesIn=NODE_NETWORK);
+        explicit CAddress(CService ipIn, uint64_t nServicesIn=NODE_NETWORK);
 
         void Init();
 
@@ -90,13 +92,13 @@ class CAddress : public CService
 
     // TODO: make private (improves encapsulation)
     public:
-        uint64 nServices;
+        uint64_t nServices;
 
         // disk and network only
         unsigned int nTime;
 
         // memory only
-        int64 nLastTry;
+        int64_t nLastTry;
 };
 
 /** inv message data */