extend bitcoin: URI with signature data, instead of serialized format

gui/qt/__init__.py

@@ -57,7 +57,7 @@ class OpenFileEventFilter(QObject):
     def eventFilter(self, obj, event):
         if event.type() == QtCore.QEvent.FileOpen:
             if len(self.windows) >= 1:
-                self.windows[0].pay_from_URI(event.url().toEncoded())
+                self.windows[0].pay_to_URI(event.url().toEncoded())
                 return True
         return False
 
@@ -140,7 +140,7 @@ class ElectrumGui:
         return int(qtVersion[0]) >= 4 and int(qtVersion[2]) >= 7
 
     def set_url(self, uri):
-        self.current_window.pay_from_URI(uri)
+        self.current_window.pay_to_URI(uri)
 
     def run_wizard(self, storage, action):
         import installwizard