Add 'crossOut' and 'disable' item overlay effects.
Add graph.getAll() endpoint.

Same as findAll() but does not throw an error on unfound items.
Reimplement item connections implementation.

Adding connections on a per item basis within the 'add' and 'update' action methods was getting unwieldy considering when changing or removing connections you have to use 'update'. The new implementation is modeled after the 'positions' API where a cascading dictionary is specified on each step that defines all connections.
Update 'how-websites-work' course to new API changes.

This includes an update to the content itself to work better with the v3 UI update which is more 'presentation' style and will follow in the next commit.
Remove incomplete item click content feature.
Remove courses dropdown

This should be on the homepage.