add more information about pkgs needed to build the lesson

Unifying links in a single file

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.

Change target of setup link from .md to site page

The link worked fine, but directing people to the setup.md file instead of the rendered page means that other links don't work - such as item 12 in the setup page: https://github.com/swcarpentry/lesson-example/blob/gh-pages/setup.md

Update a few files to make this directly readable on github

fixes styles/#87

Fixing reference to 'last episode'

Add reference to _episodes for lesson contribution

Hi,

I added a reference to the _episodes directory where the lesson material is located. As a novice (sort of) to github, it was quite difficult to figure out how to contribute. Hope this helps future contributors.

Adding structure to instructor guides/notes

Updated setup instructions to reflect new GitHub interface & changes to template

Updated the setup instructions to reflect the current GitHub interface,
and small changes to the lesson template files.

Adding accessibility changes from swcarpentry/styles

Adding Google Analytics code

Merge branch 'gh-pages' of https://github.com/swcarpentry/styles into gh-pages to accommodate accessibility changes

Fix display of double curlies using {% raw %}

Fix broken link to training memory lesson