Begin yet another model refactor

Use native ListModel which require a lot of changes, but should be
much faster than the old way which exponentially slowed down to a crawl.
Also fix some popup bugs (leave/forget).

Not working yet: side pane keyboard controls, proper highlight,
room & member filtering, local echo replacement

src/gui/Pages/Chat/Timeline/EventContent.qml

@@ -172,7 +172,7 @@ HRowLayout {
 
         HRepeater {
             id: linksRepeater
-            model: eventDelegate.currentModel.links
+            model: JSON.parse(eventDelegate.currentModel.links)
 
             EventMediaLoader {
                 singleMediaInfo: eventDelegate.currentModel

src/gui/Pages/Chat/Timeline/EventDelegate.qml

@@ -3,6 +3,7 @@
 import QtQuick 2.12
 import QtQuick.Layouts 1.12
 import Clipboard 0.1
+import "../../.."
 import "../../../Base"
 
 HColumnLayout {
@@ -65,13 +66,8 @@ HColumnLayout {
     function json() {
         return JSON.stringify(
             {
-                "model": utils.getItem(
-                    modelSources[[
-                        "Event", chat.userId, chat.roomId
-                    ]],
-                    "client_id",
-                    model.client_id
-                ),
+                "model": ModelStore.get(chat.userId, chat.roomId, "events")
+                                   .get(model.id),
                 "source": py.getattr(model.source, "__dict__"),
             },
         null, 4)

src/gui/Pages/Chat/Timeline/EventList.qml

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: LGPL-3.0-or-later
 
 import QtQuick 2.12
+import "../../.."
 import "../../../Base"
 
 Rectangle {
@@ -157,12 +158,12 @@ Rectangle {
             }
 
 
-            model: HListModel {
-                keyField: "client_id"
-                source: modelSources[[
-                    "Event", chat.userId, chat.roomId
-                ]] || []
-            }
+            model: ModelStore.get(chat.userId, chat.roomId, "events")
+            // model: HSortFilterProxy {
+            //     model: ModelStore.get(chat.userId, chat.roomId, "events")
+            //     comparator: "date"
+            //     descendingSort: true
+            // }
 
             delegate: EventDelegate {}
         }