PY3K: fix bytes/str issues in _pywt.pyx.
PY3K: fix bytes/str issues in _pywt.pyx.

kwohlfahrt/pywt,aaren/pywt,rgommers/pywt,Dapid/pywt,Dapid/pywt,rgommers/pywt,PyWavelets/pywt,rgommers/pywt,ThomasA/pywt,PyWavelets/pywt,ThomasA/pywt,aaren/pywt,grlee77/pywt,Dapid/pywt,rgommers/pywt,eriol/pywt,aaren/pywt,ThomasA/pywt,grlee77/pywt,michelp/pywt,kwohlfahrt/pywt,eriol/pywt,michelp/pywt,michelp/pywt,kwohlfahrt/pywt,eriol/pywt