Ensure we don't do collapsing of items across a prefix or suffix.
Ensure we don't do collapsing of items across a prefix or suffix.

If we have `[@doe99; for contrasting views see @smith33; @doe00]`,
we don't want to get collapsing to
`(Doe 1999, 2000; for contrasting views, see Smith 1933)`.

This isn't strictly by the spec, but it gives better results.

Closes #89.

jgm/citeproc