Following on from MDL-33513

repository/equella/lib.php needs two new functions:

function get_file_source_info($filepath)
.... returns 'Equella: originalfilename.ext' which came from filepicker which may not be the current name in Moodle.

function get_reference_details($reference, $filestatus = 0)
.... returns the data from the associated file->source field

(I just tried to do this quickly myself but I'm getting a bit lost in the repository woods!)