* replace page.root with 'base' variable that knows path level

* deal with case of trailing / in URL

* use link to figure out path for logos

* simplify path building for favicons

* baseurl isn't used in our template so it can removed
* use 'base' variable for path root instead of unecessary http request to
  site.url

* replace page.root with 'base' variable that knows path level

* deal with case of trailing / in URL

* use link to figure out path for logos

* simplify path building for favicons

* baseurl isn't used in our template so it can removed
* use 'base' variable for path root instead of unecessary http request to
  site.url

* rename variable, consolidate comments

* rename variable in template files

Close https://github.com/swcarpentry/lesson-example/issues/145.

As suggested by @gcapes.

Related with https://github.com/swcarpentry/styles/issues/80.

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.