A large scale set of changes to bibulous.py to allow nested template options:

(1) Added the functions "remove_nested_template_options_blocks()" and "toplevel_split()".
(2) Renamed "parse_bst_template_str()" as "simplify_template()".

Also, I converted the code to use a 120 chars per line convention rather than a 100 chars per line one. My printer does 120 per line by default, so it seemed silly to limit to the smaller number, despite PEP8.