- 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.
