add a callout about header IDs

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