Moderation and Stickers
* Unify new contact and new channel into one dialog
* Do not require adding a contact to message or call
* Allow moderators to moderate messages in channels
* Hide avatar, nickname, and content for moderated messages in channels
* Don't change XMPP URI link labels if they have a custom one via XHTML-IM
* If an XMPP URI is for the current conversation, hide redundant display name
* Unread count should use primary colour (possible from custom colour theme)
* Sleep hack to make "all done" notification for backups more reliable
* Allow blocking avatars and other media by hash locally
* Offer to download default sticker packs, storing CID and URL
* Send CID with known URL without uploading
* Send SIMS with hashes and filename
* Allow importing stickers made for Signal (via signal.art or sgnl:// links)
* Allow command UI cancel even if an embedded webpage is broken
* Fixes for older Android version compatibility
* Fixes for various crashing bugs