On iOS the message is sent twice, with a duplicate event_id.
It cause error on logs, in different places (synapse, mautrix, ...)

It required to fix the already existing json or reimport the stickers.

The "packs/scalar*" example already include this field, and it works.

Show sticker body in hover tooltip

Rename import.py, since import is a keyword

    from sticker.import import cmd
                 ^
SyntaxError: invalid syntax

Fixes https://github.com/maunium/stickerpicker/issues/27.

The license was initially MPLv2 as I expected the project to be a fairly
simple tiny web app, but it has already grown into multiple files. Now
that I'm going to add a server component, I'm switching the license for
future versions to AGPL like all my other non-library projects.

Fixes #11