Initial version for code review

Because the initial development was occurring on master, there isn't an easy way to do code review. This pull exists solely as a means to code review the entire project. Any changes will be put straight into master and this pull will be closed and the `initial-code-review` branch deleted. All future development will use pull requests into master to facilitate code review.
Also we check that all the scopes are of type `Scope` in the constructor, but not here. I think if we're going to do it there we should do it here too (although I'm in favor of DBC so I'd so don't check it in either place).