Big performance refactoring & various improvements

Instead of passing all sorts of events for the JS to handle and manually
add to different data models, we now handle everything we can in Python.

For any change, the python models send a sync event with their
contents (no more than 4 times per second) to JS, and the QSyncable
library's JsonListModel takes care of converting it to a QML ListModel
and sending the appropriate signals.

The SortFilterProxyModel library is not used anymore, the only case
where we need to filter/sort something now is when the user interacts
with the "Filter rooms" or "Filter members" fields. These cases are
handled by a simple JS function.

We now keep separated room and timeline models for different accounts,
the previous approach of sharing all the data we could between accounts
created a lot of complications (local echoes, decrypted messages
replacing others, etc).

The users's own account profile changes are now hidden in the timeline.
On startup, if all events for a room were only own profile changes, more
events will be loaded.

Any kind of image format supported by Qt is now handled by the
pyotherside image provider, instead of just PNG/JPG.
SVGs which previously caused errors are supported as well.

The typing members bar paddings/margins are fixed.

The behavior of the avatar/"upload a profile picture" overlay is fixed.

Config files read from disk are now cached (TODO: make them reloadable
again).

Pylint is not used anymore because of all its annoying false warnings
and lack of understanding for dataclasses, it is replaced by flake8 with
a custom config and various plugins.

Debug mode is now considered on if the program was compiled with
the right option, instead of taking an argument from CLI.
When on, C++ will set a flag in the Window QML component.

The loading screen is now unloaded after the UI is ready, where
previously it just stayed in the background invisible and wasted CPU.

The overall refactoring and improvements make us now able to handle
rooms with thousand of members and no lazy-loading, where previously
everything would freeze and simply scrolling up to load past events
in any room would block the UI for a few seconds.

TODO.md

@@ -2,20 +2,26 @@
   - `QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling)`
 
 - Refactoring
+  - Remove copyrights
+  - Remove clip props when possible
+  - `property list<thing>`
+  - See Loader.enabled and async
   - Use [Animators](https://doc.qt.io/qt-5/qml-qtquick-animator.html)
   - Sendbox
-  - Use .mjs modules
   - SignIn/RememberAccount screens
     - SignIn must be in a flickable
-  - Don't bake in size properties for components
   - Unfinished work in button-refactor branch
     - Button can get "hoverEnabled: false" to let HoverHandlers work
   - Room Sidepane
     - Hide when window too small
     - Also save/load its size
-  - When qml syntax highlighting supports string interpolation, use them
+  - When qml syntax highlighting supports ES6 string interpolation, use them
 
 - Fixes
+  - Terrible performance using `QT_QPA_PLATFORM=wayland-egl`, must use `xcb`
+  - Reloading config files (cache)
+  - Ignore @ when filtering members
+  - Tiny invisible scrollbar
   - Update state.json page when accepting an invite
   - Run import in thread and AsyncClient.olm functions, they block async loop
   - Handle import keys errors
@@ -28,10 +34,6 @@
   - Message position after daybreak delegate
   - Keyboard flicking against top/bottom edge
   - Don't strip user spacing in html
-  - Past events loading (limit 100) freezes the GUI - need to move upsert func
-    to a WorkerScript
-  - `MessageDelegate.qml:63: TypeError: 'reloadPreviousItem' not a function`
-  - Horrible performance for big rooms
   - [hr not working](https://bugreports.qt.io/browse/QTBUG-74342)
 
 - UI
@@ -40,6 +42,9 @@
       - Accept/cancel buttons
       - Transitions
 
+  - Combine events so they take less space
+    - After combining is implemented, no need to hide our own profile changes.
+  - Room last activity time in RoomDelegate
   - When starting a long task, e.g. importing keys, quitting the page,
     and coming back, show the buttons as still loading until operation is done
   - Make invite/left banners look better in column mode
@@ -59,12 +64,12 @@
       - Support \ escaping
   - Improve avatar tooltips position, add stuff to room tooltips (last msg?)
   - Accept drag and dropping a picture in account settings to set avatar
-  - When all the events loaded on beginning in a room are name/avatar changes,
-    no last event room text is displayed (use sync filter?)
 
   - Show something when connection is lost or 429s happen
   - "Rejoin" LeftBanner button if room is public
   - Daybreak color
+  - Conversation breaks: show time of first new msg after break instead of big
+    blank space
   - Replies
   - `pyotherside.atexit()`
   - Sidepane
@@ -82,7 +87,9 @@
   - Leave room
   - Forget room warning popup
   - Prevent using the SendBox if no permission (power levels)
-  - Spinner when loading past room events, images or clicking buttons
+    - Prevent using an alias if that user is not in the room or no permission
+  - Spinner when loading account, past room events, images or clicking buttons
+    - Show account page as loading until profile initially retrieved
   - Theming
     - Don't create additional lines in theme conversion (braces)
     - Recursively merge default and user theme
@@ -114,20 +121,17 @@
   - Links preview
 
 - Client improvements
+  - Image provider: on failed conversion, way to show a "broken image" thumb?
   - Config file format
-  - Set Qt.application.* stuff from C++
-  - [debug mode](https://docs.python.org/3/library/asyncio-dev.html)
   - Initial sync filter and lazy load, see weechat-matrix `_handle_login()`
     - See also `handle_response()`'s `keys_query` request
   - Direct chats category
-  - On sync, check messages API, if a limited sync timeline was received
   - Markdown: don't turn #things (no space) and `thing\n---` into title,
     disable `__` syntax for bold/italic
   - Push instead of replacing in stack view (remove getMemberFilter when done)
   - `<pre>` scrollbar on overflow
   - When inviting someone to direct chat, room is "Empty room" until accepted,
     it should be the peer's display name instead.
-  - See `Qt.callLater()` potential usages
   - Animate RoomEventDelegate DayBreak apparition
   - Room subtitle: show things like "*Image*" instead of blank, etc