rework short_disp methods * ov.h (octave_value::short_disp): Pass std::ostream as argument instead of returning std::string. Change all uses. * ov-base.h (octave_base_value::short_disp): Likewise. Change all derived classes. * ov-base-scalar.cc (octave_base_scalar<ST>::short_disp): Strip leading whitepace from number. * ov-base-mat.cc (octave_base_matrix<MT>::short_disp): Strip leading whitepace from numbers.