Standard buttons are ordered in the right way and sometimes have an
icon.

Bug: https://matrix.to/#/%23nheko%3Anheko.im/%2476PZ2m6YftX8mqGIe9ettKbh_-pEYeVRQSJBfwFzWi0?via=pixie.town&via=matrix.org&via=matrix.flexinos.tech&via=half-shot.uk

fixes #878

This replaces the are-you-sure dialog and also shows up when using
/-commands.

Closes: https://github.com/Nheko-Reborn/nheko/issues/239

# Previous commits:
#   e390c398 Allow to specify reason for removed message
#   5949173b Add function to force focus on InputDialog input field
#   9482ac4e Allow explicit selection of SSO method
#   ab05e2d8 Mobile message input (#962)

# 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 #975

When setting the default font, actually set the default font. When
setting a different font, change the application font.

fixes #801
fixes #232
fixes #224

Achtung!

Anyone German in the room, or is it just me? ;3

It seems that you need to manually destroy created objects... Great...

fixes #898

* add sendernames to state events

* Center state events and make them less tiny

That way we can autohide the scollbar if needed, it should fix some
jumping issues, it makes it possible to flick on mobile, etc.

Some related bugs:

https://bugreports.qt.io/browse/QTBUG-75223
https://bugreports.qt.io/browse/QTBUG-44902

Some clients (e.g. FluffyChat) don't have a UI for specifying the emote
title, and instead use the shortcode as the title. This sets the title
accordingly even if the emote was added through such a client and only
has a shortcode.