Release v4.2.2

Fixed

• A validation rule's file reference and inline code block are no longer written for rule kinds the compiler cannot read them back on. A syntax tree carrying one on, say, a not empty rule used to print a document that failed to compile with PLAY0141; the omission is now stated in a // TODO: comment on the line it would have occupied, and the printed document compiles. (#123)
• A handler, a performer and a rule <Name> predicate that carry both a file reference and an inline code block now print only the file reference - the one the compiler reads back - and name the omitted block in a comment, instead of writing both and failing to compile with PLAY0034, PLAY0048 or PLAY0141. (#123)