fixes #1272

This is a proof-of-concept example of inplementing a msgtype not found
in the spec.

Fixes #1363

Please note that this doesn't prompt when you try to send a message with a bad command.

See also:
https://daniel.haxx.se/blog/2023/01/08/copyright-without-years/
https://hynek.me/til/copyright-years/

fixes #1182

Also fix rerendering edited messages after keys are received.

fixes #1375
fixes #770
fixes #888

fixes #1373

fixes #1329

This should match what people expect from a chat application much
better. The biggest reason not to do this, is because some people might
paste markdown documents. For those people there is now a /cmark
command, which disables most of our extensions to cmark, including the
newline behaviour. There is a long discussion on the Fediverse and on
Github linked below.

Mastodon https://fosstodon.org/@deepbluev7/109771668066978726
fixes #757

by always sending as formatted when a newline is in the body

* Pause ParticleEmitter when not in use

* Use timer instead to pause particle system