Remove sender tooltip, and sender label, simplify MessageDelegate, add

an option to invoke GC, and update libqmatrixclient.

qml/component/DownloadableContent.qml

@@ -1,7 +1,6 @@
 import QtQuick 2.9
 import QtQuick.Controls 2.2
 import QtQuick.Controls.Material 2.2
-import QtQuick.Dialogs 1.2
 
 Item {
     property bool openOnFinished: false
@@ -15,19 +14,10 @@ Item {
         opacity: 0.4
     }
 
-    FileDialog {
-        id: locationDialog
-        title: "Please choose a location"
-        folder: shortcuts.home
-        selectFolder: true
-
-        onAccepted: currentRoom.downloadFile(eventId, folder + "/" + currentRoom.fileNameToDownload(eventId))
-    }
-
     onDownloadedChanged: downloaded && openOnFinished ? openSavedFile() : {}
 
     function saveFileAs() {
-        locationDialog.open()
+        Qt.createComponent("DownloadDialog.qml").createObject(this).open()
     }
 
     function downloadAndOpen()