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

an option to invoke GC, and update libqmatrixclient.

qml/component/AvatarContainer.qml

@@ -2,7 +2,7 @@ import QtQuick 2.9
 import QtQuick.Controls 2.2
 
 Row {
-    readonly property bool avatarVisible: !sentByMe && aboveAuthor !== author || section !== aboveSection
+    readonly property bool avatarVisible: !(sentByMe || (aboveAuthor === author && section === aboveSection))
 
     spacing: 6
 
@@ -15,14 +15,6 @@ Row {
         visible: avatarVisible
         source: author.avatarUrl != "" ? "image://mxc/" + author.avatarUrl : null
         displayText: author.displayName
-
-        MouseArea {
-            anchors.fill: parent
-
-            hoverEnabled: true
-            ToolTip.visible: containsMouse
-            ToolTip.text: author.displayName
-        }
     }
 
     Rectangle {