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
We need to make sure they are inferred again when elaborating methods,
so substitute in a _ in method types before substituting in the explicit
parameters.
In future, it might (probably will) also be useful to allow giving the
implicit parameters explicitly when defining implementations.
Fixes#374
