While the discussion about how to refactor test framework is not
finished (#1654), make this change: move `rm -rf build` in the
beginning of the test. For these reasons:
* it is useful to inspect the contents of the `build` directory
especially after the test failure
* if build crashes mid-test (e.g. process killed), next run should
not be affected by the `build` directory from the previous run
- Added initial implementations for terms and values
- Error messages converted to pretty printer
- Colorization for error messages
- Color and console width option both as command line and repl command
This improves coverage checking, because it can now see that things like
(Z = S x) and (x = S x) are empty. Previously, it only checked that all
possible constructors had a disjoint index. Now, it looks for matches
and checks for disjointness in the matches, which catches a lot more
things especially with equality.
