Use updated routing syntax.
issets on url chunks
Merge branch 'develop' of github.com:unikent/of-course into feature/fix-urls-for-new-flight

Conflicts:
	public/index.php
Correct links for 404 error page.
Show both subject areas + ensure explicitly set headers are actually being set if we can.
Merge pull request #111 from unikent/feature/fix-urls-for-new-flight

Update routing for newer flight version