* cppcheck stuff

* Update src/ui/RoomSettings.cpp

Co-authored-by: DeepBlueV7.X <nicolas.werner@hotmail.de>

* Update src/ui/RoomSettings.cpp

Co-authored-by: DeepBlueV7.X <nicolas.werner@hotmail.de>

* Fix linting

Co-authored-by: DeepBlueV7.X <nicolas.werner@hotmail.de>

Since this is used across different threads, we have to delete it on the
event loop.

Thank you, q234rty, for the help with debugging this.

* First draft of unread line feature.

* Minor visual fix.

* Removed unnecessary ternary operator.

* Extended unread line functionality to work on minimised window or focusing another window.

* Fix for unread line not showing when last read message is hidden.

* Minor performance improvement. Fix for misbehaving event2order DB at application start.

* Fix for possible performance issues when user has joined a large number of rooms.

* Fix for breaking macos and clazy builds.

* Changed on windows focus function to refresh unread line if room is unread.

* Unread line is removed when user sends a message.

* Linting.

* Fixed unread line to work in standalone room windows.

* Switch isRoomUnread for index 0.

* Merged try/catch blocks.

* Fix for crash on opening a room invite.

* Call fullyReadEventId function when used instead of storing it and passing it through.

* Function that was meant to sync the unread line was relying on an async function, oops.

* Linting again.

* More linting...

* Minor changes.

The cache is only approximate, i.e. it doesn't skip edits and similar,
but this might be good enough? Also no migration right now.

Speeds up startup by about 5x on my system.

Half the startup time is now loading the powerlevels for each room. We
can probably lazily load those too in the future.

# Previous commits:
#   5949173b Add function to force focus on InputDialog input field
#   9482ac4e Allow explicit selection of SSO method
#   ab05e2d8 Mobile message input (#962)
#   12a6da01 If you replace the txn id, replace a string the length of the txn id...

fixes #519