Add automated tests to the toolchain #1

Amazing project, I'm looking forward to the results!

First of all, I strongly recommend to add my automated tests from PACE-2017 to your toolchain. One way of doing this would be to add https://github.com/holgerdell/td-validate as a submodule, perhaps under tests/td-validate, and add a cargo test command (or whatever is considered to be good form in rust). This command should then probably compile td-validate, and run autotest-tw-solver.py on your program.