BIP144: Handshake and relay (receiver side)

Service bit logic by Nicolas Dorier.

Only download blocks from witness peers after fork.

src/qt/guiutil.cpp

@@ -909,6 +909,9 @@ QString formatServicesStr(quint64 mask)
             case NODE_BLOOM:
                 strList.append("BLOOM");
                 break;
+            case NODE_WITNESS:
+                strList.append("WITNESS");
+                break;
             default:
                 strList.append(QString("%1[%2]").arg("UNKNOWN").arg(check));
             }