This writes the SSL certs to a temporary file on startup and then
uses environment variables to control OpenSSL and curl so that
they use them. We have to do this because OSX no longer ships the
normal ca pems, and we statically link with these libraries.
* Add cross-compilation for `lmdb`.
* Got built caching working in CI with `cachix`.
* Cache cross compilation dependencies and toolchains.
* Do release builds in CI.
* Upload release builds to `bootstrap.urbit.org` on successful build.
* Lots of optimization work for CI.
* Boot from a solid pill in CI and load arvo with `-A`.
* Increase `vere` HTTP timeout to 15m.
* Move extraneous stuff out of pkg/urbit/*
* s/urb/herb/g
* Removed some boilerplate for `urbit` builds.
* Build urbit tests and run them in the nix build.
