WalletManager: non-blocking mining status updates

pages/Mining.qml

@@ -258,14 +258,18 @@ Rectangle {
         }
     }
 
-    function update() {
+    function onMiningStatus(isMining) {
         var daemonReady = walletManager.isDaemonLocal(appWindow.currentDaemonAddress) && appWindow.daemonSynced
-        appWindow.isMining = walletManager.isMining()
+        appWindow.isMining = isMining;
         updateStatusText()
         startSoloMinerButton.enabled = !appWindow.isMining && daemonReady
         stopSoloMinerButton.enabled = !startSoloMinerButton.enabled && daemonReady
     }
 
+    function update() {
+        walletManager.miningStatusAsync();
+    }
+
     MoneroComponents.StandardDialog {
         id: errorPopup
         cancelVisible: false
@@ -286,4 +290,8 @@ Rectangle {
     function onPageClosed() {
         timer.running = false
     }
+
+    Component.onCompleted: {
+        walletManager.miningStatus.connect(onMiningStatus);
+    }
 }