Linalg 3 lu

lu take permutation into account.
all features (as_terminal assign_swap etc.) devlped in qr and nseig passes are used there
tests are for real complex and sub
compute the inverse permutation of ip.
If ip is the list of indices defining a permutation of 1:n  i->ip(i)
the inverse permutation can be computed by saying that inv is of same size as ip
and inv(ip)=1:n