Make pyobject callable by users (to convert input) This makes "pyobject(...)" behave more a cast or typical constructor call. This should supercede the "fromPythonVarName" hack in some cases. * @pyobject/dummy.m: Use new pyobject call. * @pyobject/pyobject.m (@pyobject/pyobject): Redo ctor. * python_to_octave.cc: Use new pyobject ctor.