Packaging and build systems #24

Things are a disaster. I have to unset SDKROOT when on macOS to get a build to work. (But I need it set to get Haskell to work.)

Ideally we should have:

• opam package for libdash
• change .travis.yml to actually build things rather than use Docker
• build on multiple OSes
• make -j4 or something, i mean come on breaks lem and maybe us too?
• add back Modernish tests
• change to just depend on an opam package for lem
• build uses lem OPAM package, submodule removed
• opam package for smoosh
• build just uses these packages (with local pinning?)
• have a Travis build that actually tests Docker (and Vagrant, too?) best approach: use OPAM!
• log test output and post somewhere meaningful (run other shells, too? or is all this a separate repo?)