Alignments and a CLI interface

[nikvaessen]

This PR adds the following:

1. The compute_measures output dictionary returns the results of the editops so that users can use the alignment
2. The compute_measures output dictionary returns the processed ground-truth and hypothesis sentences so the alignment can be easily processed, and the pre-processing can be sanity-checked.
3. Add a method visualize_measures which pretty-prints the alignments and computed measures.
4. Add a simple CLI wrapper which uses 2 text files as input.