Made the stupid mistake of committing bibulous_test.py when I had commented out several of the tests. Not good form.
Added the method write_auxfile() to the Bibdata class. This replaces a block of code that was in bibulous_test.py.
Modified 'test2' in the testing suite to use citekeys for reference labels rather than just numeric values. Also made some cosmetic changes to test8.
Added test9 to the testing suite.
Added a case-sensitive test to test1 of the testing suite. This turned up a surprisingly tricky bug to fix. I had to add an option 'case_sensitive_fieldnames' and, to make sure it got used correctly, I had to change the order in which files get parsed to make sure that the BST files get parsed before the BIB files.