Fixes bug in flookup/apply down() (binary search of arcs in apply_down() did not always recognize ? as equivalent to @ if arcs are sorted and apply_down() used the binary search strategy).
Fixes bug in flookup/apply down() (binary search of arcs in apply_down() did not always recognize ? as equivalent to @ if arcs are sorted and apply_down() used the binary search strategy).

alishir/foma,alishir/foma,alishir/foma,alishir/foma