'Wrong number or type of arguments' error in MultiscaleResampler

[Sam Preston]

This is related to Issue #64, where default NULL arguments to StreamT were being incorrectly converted to 0 instead of None in python code. Updates to SWIG fixed most of those issues, but they still seem to exist in MultiscaleResampler for some reason. Workaround is to pass None as the StreamT argument (instead of leaving the default).