More readable output when comparing very long strings

[zkochan]

I use tap-diff in mos to test markdown files. Basically mos can generate some parts of the markdown files. The testing part checks whether the generated version matches the current one in the file system.

The markdown files are huge and the output is hard to read. Lets suppose I have renamed my package to mos2 and ran mos test. The output will be hard to read

There are two reasons it is hard to read:

1. The newlines are displayed as \n instead of actual newlines
2. There is too much noise, lines that match are included in the output as well.

The output would be a lot more readable, if it would be displayed like in diff-so-fancy

reference: mos/issue#59

[zkochan]

This package does a good output for string diffs https://github.com/HiroakiMikami/pdiff
It can probably be used in tap-diff