This also removes the GROUP/UNGROUP-specific undo actions.
This also fixes a bunch of undo bugs when duplicating
group members, creating pins, etc.
This also fixes some undo bugs when dividing wires etc.
This also fixes some bugs with new sch items not
being created within an entered group.
Recommendation is to avoid using the year nomenclature as this
information is already encoded in the git repo. Avoids needing to
repeatly update.
Also updates AUTHORS.txt from current repo with contributor names
