Vandermonde matrix, vander() function extension

Uses the more common definition of the Vandermonde matrix with power zero to the left, and adds the ability to create non-square matrices for more flexibility.

V=vander2(v,k)=[v.^0 v.^1 ... v.^k];
where length(v)=n and dim(V)=[n, k].

Note that replacing the original vander() function can cause other functions to fail.