jekyll version: jekyll 3.2.1

Updating mailmap and AUTHORS before release

Tidying up after consolidating links

Rev 7da36a56 added a new row to the syllabus table with only 11 columns (instead of 12), which broke layout.
This fix adds the missing space.

Close #81

Close #80

Including mention of Library Carpentry in include files

Merge last changes on https://github.com/swcarpentry/styles/

Knit episodes only when any one RMarkdown source changes

Adding Google Analytics

add more information about pkgs needed to build the lesson

Unifying links in a single file

Adding comments on purposes of include files

Using page.previous and page.next for links instead of loop

lesson.scss: 2em left padding for lists

Auto-generating IDs for glossary items

Fixing layout of descriptions of standard pages

1.  Create file `_includes/links.md` with definitions of all links.
2.  Replace links at the bottom of Jekyll'd `.md` files with inclusion of that file.
3.  Modify `bin/lesson_check.py` to load and check definitions in this file.

This eliminates most redundancy in link definitions, though
`CONTRIBUTING.md` and `README.md` still contain their own links, since
they are not Jekyll'd.  Note that we *cannot* put the links into
`_layouts/*.html` (or even `_layouts/something.md`) because of the
order in which Jekyll expands things - we have to explicitly include
it in each page.