Embassy now indicates the initial replay
Web client now indicates replay status
Web client now splits messages into areas

Well, maybe.  I forgot to download the CDN-hosted scripts while at work,
and my home is offline, so I'm just coding blindly.
Reorganize some files
Reorganize files
Import 3rd party JavaScript libraries

I went out to a pub, drank a pint of Guinness, and curled my external
dependencies.  Good times!
Web client now looks prettier
Fake throttling and replay progress bar
Basic UI for channel input
Scroll up on render
Styling tweaks
Write something in the README
Client: factor out message model
Accept commands from HTTP client + client events

This commit introduces the possibility for the client to POST commands
to the embassy, which will be parsed, saved in the archives, and sent
back to the client.  The set of commands is also extended to enable
custom client-only events, versioned and namespaced by client vendor.
Simple "mark as read" feature
Reorganize file structure