* configure.ac: Added some hints in comments.
* glom/libglom/python_embed/pygdavalue_conversions.cc:
  Do not use PyInt_Check if building with python 3,
  because python 3 does not seem to have integer types.
  Use PyUnicode_Check() instead of PyString_Check().
  This seems to be appropriate for python 2 too.
* glom/main.cc: Do not call PySys_SetArgv() if building
  with python 3 because we would need to massage the
  arguments into wchar*, and we do not know why we call
  it anyway.
* glom/python_embed/glom_python.cc: Do not call
  Py_FlushLine() if building with python 3, because it
  does not exist in python 3 and is apparently
  unnecessary.
* glom/test_pyembed.cc: USe PyUnicode_Check() instead
  of PyString_Check(). See above.
  Again, do not call Py_FlushLine() with python 3.
* glom/test_pyembed_singleline.cc: Do not call
  PyFlushLine() with python 3.

To build for Python 3, you'll need to do something like this:
export PYTHON=python3.3
  (do this before starting jhbuild, if you are using jhbuild).
configure --with-boost-python=boost_python-mt-py33
  (or autogen.sh if building from git.)
You will need to have built pygobject with Python3 support.