Fixes readability issues in the userprofile.

fixes #440

Fixes messages in room flickering and being stuck

fixes #760
relates to #770
relates to #789

fixes #683
relates to #571

This was a bit of a journey:
https://github.com/matrix-org/matrix-doc/pull/3471
But it should work now and we now use the UIAHandler everywhere.

fixes #670

Add support for listing devices that do not support encryption, add support for logging out devices.

Ticks off another box in #23!

The file ending list is translated, so all the translations are updated
too.

This ports the leave room dialog to QML, everywhere. There are now no differences between the various leave dialogs.

Showing the bootstrap state and showing there are unverified devices is
still missing.

Added support for refreshing the device list, marking current device with a checkmark instead of a lock

- add missing mimetype
- allow removal of images from pack
- allow GIF as a format
- don't divide size by 2 if the image is very small already

We explicitly set a parent. We can't assign to
ApplicationWindow.transientParent though, only to
Window.transientParent, so we just call setTransientParent in C++.