Function: groupchardet
Section: combinatorics
C-Name: groupchardet
Prototype: GGD1,L,
Help: groupchardet(G, chi, {o=1}): return the determinant character of the
 character chi.
Doc: Let $\chi$ be the character of some representation $\rho$ of the group $G$,
 where a polynomial variable is to be interpreted as an $o$-th root of 1.
 For instance, if \kbd{[T,o] = groupchartable(gal)} the characters
 $\chi$ are input as the columns of \kbd{T}.

 Return the degree-$1$ character $\det\rho$ as the list of $\det \rho(g)$,
 where $g$ runs through representatives of the conjugacy classes
 in \kbd{groupconjclasses(gal)}, with the same ordering.

