BibDocFile: get_icon() for smallest size icon
- Updates get_icon() function to return the BibDocFile associated with the subformat CFG_BIBDOCFILE_ICON_SUBFORMAT_RE, or, if this does not exist, the smallest size icon available. (closes #1350) (closes #1743)
Signed-off-by: Ludmila Marian <ludmila.marian@gmail.com>
Reviewed-by: Samuele Kaplun <samuele.kaplun@cern.ch>