mdbtools can open the new .accdb file format if the IS_JET4 macro is modified to allow mdb->f->jet_version to have a value of 2.
The long term change should probably be to change the name of the macro to IS_JET4_PLUS, but this patch keeps the changes needed to just the mdbtools.h header.
Modification of IS_JET4 macro to allow .accdb files to be opened