* Refactor widget items to use same interface

* Support audio, video, generic file for pasting

* Add utils function for human readable file sizes

* Set correct MIME type for media messages

This change also determines the size of the upload once from the
ContentLengthHeader, rather than seeking the QIODevice and asking for
its size. This prevents any future trouble in case the QIODevice is
sequential (cannot be seeked). The MIME type is also determined at
upload once, rather than using the QIODevice and the underlying data
inside.

* Allow for file urls to be used as fall-back

This fixes an issue on macOS which uses `text/uri-list` for copying
files to the clipboard.

fixes #228 

fixes #208

We can't rely solely on the number of the returned messages
because it could be zero if all the event types are unknown.

fixes #168

fixes #87

fixes #184
fixes #209

This can happen when a new room is being created from a different client and thus is created
with no known state to the local client.

fixes #226

[ci skip]

Show a better message on the login screen after an initial sync failure.

Create space for checkmark beforehand

fixes #217 

Updated Fedora installation instructions

[ci skip]

Signed-off-by: Vitaly Zaitsev <vitaly@easycoding.org>

fixes #181

Signed-off-by: Vitaly Zaitsev <vitaly@easycoding.org>