1. Fix bug in test builds that was causing failures for some reason I
still don't understand.
`tee` output to stderr was failing with "resource temporarily
unavailable". The hack that fixed it was to simply write the herb
output to a file and dump it to stdout after it fully completes.
2. sh/cachix works without CACHIX keys. Simply doesn't upload in that case.
3. Write code to cache testbus builds (disabled for now)
4. fakeship builds get further in bootstrap sequence before committing.
This fixes problems with PRs from forked repos and enables the scripts
to be run locally.
* 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.
