To avoid showing them erroneously would mean keeping track of used
message ids which seems like more work than justified by the feature.

Fixes #1026

To more cleanly separate views and models and to make MUC in headless
mode more viable.

Refs #1032

* Distinguish between CSN messages and other types of messages
* Properly clear previous notifications
* Better handling of notifications from multiple users (in MUC)
* Rename methods to make clarify intent

* replace geoURIs by link to openstreetmap

* Added testcase

They don’t have an automated redirection, nor HSTS preload, so it is
better to directly point to the HTTPS version of their website.

Thanks to @linkmauve

and out of the MUC views plugin.

Refs #1032

* checkForReservedNick
* parseRoomFeatures
* sendConfiguration

Refs #1032

The theme is still bootstrap3 based and there isn't enough time
currently to redo on bootstrap4.

Details here: https://prosody.im/issues/1121

- for subscription requests
- when entering chat rooms

Otherwise the contact stays visible under "Pending Contacts" although
the subscription request has been accepted.

when it's created due to a new contact being added.

Was previously in the wrong place.