Handle statement crossrefs in multiple citations

[jdutant]

Crossreference to a statement followed by a citation is merged by Pandoc:

@sta:claim [@smith2002, 12]

Results in:

[ Para
    [ Cite
        [ Citation
            { citationId = "sta:claim"
            , citationPrefix = []
            , citationSuffix = []
            , citationMode = AuthorInText
            , citationNoteNum = 1
            , citationHash = 0
            }
        , Citation
            { citationId = "smith2002"
            , citationPrefix = []
            , citationSuffix = [ Str "," , Space , Str "12" ]
            , citationMode = NormalCitation
            , citationNoteNum = 1
            , citationHash = 0
            }
        ]
        [ Str "@sta:claim"
        , Space
        , Str "[@smith2002,"
        , Space
        , Str "12]"
        ]
    ]
]

Currently, the filter doesn't handle this; it ignores Cite elements that contain multiple citations. The above results in a 'citation not found'.

temporary hack

In the meanwhile users need to separate statement cross-reference and citation, e.g. using an invisible zero-width non-joiner character:

@sta:claim ‌[@smith2002, 12]

desired behaviour

When the filter encounters a Cite with multiple citations, the first of which is a statement cross-reference, it should extract the latter.

Potential risk: a cite key identical to a statement key, the user is trying to cite the former and the filter mistakenly captures the latter. That's marginal, and a risk the user already faces just by using the filter and giving the same key to a statement as a bibliography entry.