Security Fixes, Tagging Improvements, Dialling Fixes

* Switch to Snikket's WebRTC build (fixes F-Droid security advisory)
* Fix for MUC configuration bug
  NOTE: This was causing all newly created private groups to be public.
        Please check that your existing groups are private!
* Support latest version of Bookmarks2
* Tags on MUC bookmarks (only with bookmarks2)
* Show system contact groups on the tags of system contacts
* Use network locale when dialling or adding a contact
* Use SIM locale when syncing contacts, special case JMP SIM to be USA
* SASL2/bind2 merged from upstream, see: https://blog.prosody.im/fast-auth/
* Serve files over Bits-of-Binary (if small enough and trusted requester)
* Support for basic incoming SIMS (XEP-0385)
* Fix command-button-on-every-message bug
* jid-single and jid-multi command fields are clickable
* OLED Black Theme (thanks Jeffrey Miller!)
* Fixes for some crashing bugs