Python wrapper for qpid-cpp cannot handle unicode data.

The Python wrapper for the qpid-cpp library cannot handle unicode data properly. The reason for this is how unicode objects are encoded in the PyToVariant function, which is located in the "swig_python_typemaps.i" file.

PyToVariant uses the PyUnicode_AS_DATA to encode the data, but that is wrong. It returns the internal representation of the data, which usually is UTF-16, but that depends on how the Python libraries where built. The VariantToPy function correctly uses the PyUnicode_DecodeUTF8 function, but that is not compatible with the data returned from PyUnicode_AS_DATA.

The proper solution is to either use PyUnicode_EncodeUTF8 or PyUnicode_AsUTF8String, including proper error handling.