Updated sidebar to expand to show clicked subtopics, and no sliding.
Remove height specification on slimScroll.
Styling tweaks to sidebar.
Mark intermediate topic nodes as active in sidebar.
Merge branch 'develop' of github.com:learningequality/ka-lite into expanding_sidebar
Properly update URL when switching content items within a leaf topic.

Also, do nothing when clicking on a node in the topic tree that's already
been selected.
Remove duplicate load_entry_progress key.
Merge pull request #2516 from jamalex/expanding_sidebar

Updated sidebar to expand to show clicked subtopics, and no sliding.