Return empty matrix when linspace called with 0 points (bug #45820) * NEWS: Announce change. * data.cc (Flinspace): Verify input N is scalar. Verify inputs BASE, LIMIT are scalar/vectors. Add BIST tests for input validation, complex values, class of output, Matlab compatibility. Clarify documentation about vector inputs. * CMatrix.cc, CRowVector.cc, dMatrix.cc, dRowVector.cc, fCMatrix.cc, fCRowVector.cc, fMatrix.cc, fRowVector.cc: Return empty matrix when N < 1.