Updating to handbook as canonical source for CoC

don't break words in code

Update repo_check.py with new GitHub labels

As @marwahaha said

> "master repository" feels overloaded,
> since typically "master" refers to a branch name.

We are going to use "originating repository".

Close #211

Close #217

Fix source of typo #646

Link DOIs to preferred resolver

Remove out-of-date CoC language

fix svg files

Related with lesson-example/pull/172

Fix broken link for Contact

Add current year to copyright of workshop footer

Updated lesson_initialize

Fix CSS to use .language-X class

Advise users not to edit .md files generated from .Rmd files

secure hyperlinks to pre-empt server-side HTTPS redirects

Reorganized description of process for contributing to clarify/increase readability

Changed the keyword for emailing from 'contact' to 'email' per https://github.com/swcarpentry/styles/issues/178 and changed the description for how to use GitHub to reflect usage of the web interface.

Fix bin/lesson_initialize.py

If _extras/figures.md exists,

    $ ./bin/lesson_initialize.py

will return

    Warning: _extras/figures.md already exists.
    **Exiting without creating files.**