Parsing:  Generalized state type on readWith.
ParserState:  Replace stateTitle, stateAuthors, stateDate with stateMeta.
RST reader:  Use stateMeta.
RST reader:  Improved metadata.

Treat initial field list as metadata when standalone specified.

Previously ALL fields "title", "author", "date" in field lists
were treated as metadata, even if not at the beginning.