Make replies default to privacy settings of the status being replied to

StreamEntry model. Simply render Salmon slaps as they are needed

Text for link to other instances

to only those from local users; Add link to "extended information" to
getting started in the UI; Add defaults for posting privacy; Change
how publish button looks depending on posting privacy chosen

work flawlessly was a nightmare). WARNING: This commit makes the web UI connect to the streaming API instead
of ActionCable like before. This means that if you are upgrading, you should set that up beforehand.

redis-backed "mentions" timeline as redundant (given notifications)

Do not require e-mail address changes to be re-confirmed, it's only trouble for no real benefit

for extremely wide monitors

improved how "show more" link looks

Federate spoiler_text using warning attribute on <content /> instead of a <category term="spoiler" />
Clean up schema file from accidental development migrations

now return empty hash instead of throwing a 404 error. When following,
merge into timeline will filter statuses

application website validation, don't link to app website if website isn't set,
also comment out animated boost icon from #464 until it's consistent with non-animated version