Terra 1.0.0

Terra is a bit unusual in that it consumes LLVM (another large project), and in ways that LLVM doesn't seem to have been quite intended for. So the Makefile build was always a bit of a chore because we had to reverse engineer a bunch of build stuff that wasn't exposed in a sane way.

The biggest win for CMake (aside from doing Windows at all) was that LLVM uses CMake, so we get access to LLVM's first-party CMake configuration. On the whole it tends to be a lot more sane to get what we need this way, and I've mostly been able to stop tearing my hair out every time I start up Terra on a new machine these days.