Implements first pass of sidebar router navigation.
Adds url modification for topic sidebar clicks.
Adds sidebar 'back' url modification.
Allows url navigation to content from sidebar.
Adds styling and imports for rendering exercises in overlay on knowledgemap.
Cleans up, renames methods, changes URL.
Intercepts Leaflet.js zooming to change map zoom levels.
Adds navigation routing/handling to knowledgemap.