Add maximum width to user name in profile

Layout is: padding | text | margin | button | padding
Therefore we subtract 2x padding, 1x margin and 1x button from
width. And an extra button for some reason. 

resources/qml/dialogs/UserProfile.qml

@@ -138,6 +138,9 @@ ApplicationWindow {
                 color: TimelineManager.userColor(profile.userid, Nheko.colors.window)
                 font.bold: true
                 Layout.alignment: Qt.AlignHCenter
+                Layout.maximumWidth: parent.width - (Nheko.paddingSmall * 2) - usernameChangeButton.anchors.leftMargin - (usernameChangeButton.width * 2)
+                horizontalAlignment: TextInput.AlignHCenter
+                wrapMode: TextInput.Wrap
                 selectByMouse: true
                 onAccepted: {
                     profile.changeUsername(displayUsername.text);
@@ -145,6 +148,7 @@ ApplicationWindow {
                 }
 
                 ImageButton {
+                    id: usernameChangeButton
                     visible: profile.isSelf
                     anchors.leftMargin: Nheko.paddingSmall
                     anchors.left: displayUsername.right