Function: rnflllgram
Section: number_fields
C-Name: rnflllgram
Prototype: GGGp
Help: rnflllgram(nf,pol,order): given a pol with coefficients in nf and an
 order as output by rnfpseudobasis or similar, gives [[neworder],U], where
 neworder is a reduced order and U is the unimodular transformation matrix

