Function: msnew
Section: modular_symbols
C-Name: msnew
Prototype: G
Help: msnew(M): M being a full modular symbol space, as given by msinit,
 return its new cuspidal subspace.
Doc:
 $M$ being a full modular symbol space, as given by \kbd{msinit},
 return the \emph{new} part of its cuspidal subspace. A subspace is given by
 a structure allowing quick projection and restriction of linear operators;
 its first component is a matrix with integer coefficients whose columns form
 a $\Q$-basis of the subspace.
 \bprog
 ? M = msinit(11,8, 1); \\ M_8(Gamma_0(11))^+
 ? N = msnew(M);
 ? #N[1]  \\ 6-dimensional
 %3 = 6
 @eprog
