Only the dmarc_version and dmarc_request tags require ordering.
Added a spec for ignoring unknown tags.
Added a tag_rule helper method.
Ignore invalid values.
Add a Parslet::Transform to pretty our parse tree.
More fiddling with the parse tree.
Renamed errors.rb to exceptions.rb.
Removed old coercion code.
Fixed our coercion of fo.
Fixed a typo.
Added Transform specs.