Remove Visible, Move and Scroll classes.
Add placeholder test file.
Move #state to public, fix tests.
Reset dependent repositories.
Update documentation.
Fix tests.
Add #all to Buffers, Cursors and Focus for consistency.
Update minitest and simplecov versions.
Convert Events into a repository module;

- Remove #events from API.
Move #reset and #registered? to Repository.
Move #all to Repository for repositories.
Move #registered to Repository.
Move #find to Repository.