qml: add setters to QEAmount to allow updating values, as replacing QEAmount instances

makes Qt unhappy in a few cases when it still holds references to the old instance, which
happened occasionally in e.g. qetxfinalizer

electrum/gui/qml/qetypes.py

@@ -36,6 +36,12 @@ class QEAmount(QObject):
             return 0
         return self._amount_sat
 
+    @satsInt.setter
+    def satsInt(self, sats):
+        if self._amount_sat != sats:
+            self._amount_sat = sats
+            self.valueChanged.emit()
+
     @pyqtProperty('qint64', notify=valueChanged)
     def msatsInt(self):
         if self._amount_msat is None: # should normally be defined when accessing this property
@@ -43,6 +49,12 @@ class QEAmount(QObject):
             return 0
         return self._amount_msat
 
+    @msatsInt.setter
+    def msatsInt(self, msats):
+        if self._amount_msat != msats:
+            self._amount_msat = msats
+            self.valueChanged.emit()
+
     @pyqtProperty(str, notify=valueChanged)
     def satsStr(self):
         return str(self._amount_sat)
@@ -55,6 +67,12 @@ class QEAmount(QObject):
     def isMax(self):
         return self._is_max
 
+    @isMax.setter
+    def isMax(self, ismax):
+        if self._is_max != ismax:
+            self._is_max = ismax
+            self.valueChanged.emit()
+
     @pyqtProperty(bool, notify=valueChanged)
     def isEmpty(self):
         return not(self._is_max or self._amount_sat or self._amount_msat)