Release v1.8.0

Added

• rule <Name> as a validation rule kind, for a rule whose logic is an arbitrary predicate: orgNumber rule BeAValidOrganizationNumber message "Must be a valid organization number". It carries message like any other rule, and works on both command and concept validation. (#47)
• A named rule can now carry its own implementation as an indented body under the rule line, the same way handler and reactor triggers do: a file <Path> reference, or an inline csharp block. Both are optional — a bare rule <Name> is still valid for logic that stays outside the document entirely.

Fixed

• A rule whose logic could not be expressed was left out of the document entirely, so a property with two declarative rules and three predicates read as a property with two rules — with no way for a reader to tell "nothing further constrains this" from "the rest could not be written down". (#47)
• The VS Code extension's TextMate grammar was missing the rule keyword, so it highlighted as plain text there even though the Monaco tokenizer recognized it.