D2h visual

[Santhip-msk]

Updated css for diff2html line folding..

[rtfpessoa]

Overall looks good to me.
Before we can merge this there are a couple of things that need to be fixed:

• As this changes the templates we need to release a new major version so you need to at least have breaking: in one of the commits for the version to be bumped
• Test should be passing and we should add a couple of cases with the folding
• Remove yarn.lock as we now use package-lock.json with npm and fix conflicts
• Remove debugger statement
• Update the readme with docs

Thanks a lot for your contribution, this is a great PR and lot's of people have requested this previously, so I think it will be loved.

Let me know if you need help with anything.