gui: send using external signer

src/qt/walletmodeltransaction.h

@@ -27,6 +27,8 @@ public:
     QList<SendCoinsRecipient> getRecipients() const;
 
     CTransactionRef& getWtx();
+    void setWtx(const CTransactionRef&);
+
     unsigned int getTransactionSize();
 
     void setTransactionFee(const CAmount& newFee);