Adds a Memo class.
Memos pass a specified object to their blocks.
Adds collections and changes to them.
The model controller vends a UI context.
Use real responses for the static API.
Adds a collection view controller.
Removes the obsolete collection controller.
Adds a memo dependency protocol.
Adds observation targets, which are themselves memo dependencies.
Memos can be greedy, have dependencies, and can ignore nil values.
Collection changes can be applied to table views.
Collection view controllers have a data source.