This is a rework of #1798 to facilitate a simpler web stack.
# Demo
View http://swarmgame.net/
NOTE: Requires IPv6
# Motivation
Hosting cost is a main motivation. Cost per month for an EC2 instance, RDS, and the requisite other services approaches >$50 per month. In contrast, the lowest-tier Lightsail instance is $3.50/month.
The deployment process is of course simplified.
An incidental benefit to using SQLite is reduced latency of web requests; we no longer need to fetch credentials from an AWS API to connect to Postgres.
## Changes
Major changes:
* Use `sqlite` instead of `postgres`
* Use Docker to build a statically-linked deployable binary, rather than deploying the app within a Docker image
Fortunately, the API of `sqlite-simple` is near-identical to that of `postgresql-simple`, so most of the code change there is just to rip out AWS-specific stuff and Postgres connection info. I have no hesitation to delete this code since if we ever want to use the previous stack again, we can just look at #1798.