cwrc_entry.rng changes [MRB]

- Made element AUTHORSUMMARY repeatable in the parent element ENTRY.
- Created the element LISTBIBCITS, which is a child element of ENTRY,
and which contains one or more BIBCITS or P child elements.
- Created the element FRONT, which is a child element of ENTRY, and
which contains one or more of the following elements: CHRONSTRUCT,
DATASTRUCT, HEADING, KEYWORDCLASS, P, and RESEARCHNOTE.