The current spelling is not strictly wrong, but flagged as unusual or
historical by some authorities. It is also found fault with many
spell checkers. Thus we decided to move to the more standard "-ible"
form once and for all.
See #10678 for discussion
This last part updates the layout format and changes collapsable color.
This will all also all be backported to 2.3.x, for the sake of backwards
compatibility (cherry-picking).
(cherry picked from commit 4345331870)
This entails a change of getAbbrAuthor to getAuthorList (the default is
still abbreviated with respect to MaxCiteItems, but the list can be, at
explicit request, shortened or full notwithstanding MaxCiteItems.
