Various 'Master broken!' fixes

As I am working through the code and tests, here are the things that I think should/could be fixed. I'll try to separate each thing into it's own commit, so they could be cherrypicked out later if necessary.

First, I added the MaybeConsumerOf Moox::Type.The currently used form `Maybe( Consumerof['Role'] )` seems not to work as intended. This type should be able to replace it with a nicer syntax but mainly correct functionality.

More commits in this branch to be expected