Moved PushGetBlocks to main.cpp to eliminate dependence of net.cpp on CBlockLocator.

src/net.h

@@ -600,7 +600,6 @@ public:
         }
     }
 
-    void PushGetBlocks(CBlockIndex* pindexBegin, uint256 hashEnd);
     bool IsSubscribed(unsigned int nChannel);
     void Subscribe(unsigned int nChannel, unsigned int nHops=0);
     void CancelSubscribe(unsigned int nChannel);