* Add configurable history length
This allows servers to decide the max length of each history item they
want to store! Some users might have much larger history lines than
others.
This setting can be set to 0 to allow for unlimited history length. This
is not recommended for a public server install, but for a private one it
can work nicely.
* Format lol
This can be used in the future for sync so that we can be more
intelligent with what we're doing, and only sync up what's needed
I'd like to eventually replace this with something more like a merkle
tree, hence the hash field I've exposed, but that can come later
Although this does include a much larger number of count queries, it
should also be significantly more cache-able. I'll follow up with that
later, and also follow up with using this for sync :)
* Switch to Cargo workspaces
Breaking things into "client", "server" and "common" makes managing the
codebase much easier!
client - anything running on a user's machine for adding history
server - handles storing/syncing history and running a HTTP server
common - request/response API definitions, common utils, etc
* Update dockerfile
