make it explicit in the generated source code what is an identifier string constant and what is a normal string constant that just happens to get interned

support running tests without running Cython to test the generated code under different Python versions (including Py3)

put the annotated .html file next to the .c file to fix annotation when the .c file is not in the same directory as the .pyx file

We ignore *.pyc, vim swap files, build results under BUILD/ and Lexicon.pickle

This is handy, because otherwise, say after runtest.py run, 'hg status' shows
lots of unrelated info, thus lowering signal-to-noise ratio.

Works with test cases for a single class, have not dealt with subclass issues
yet.

make test for new style exceptions run on all Python versions by not actually testing for new style exceptions :)