Converted most of the regex definitions to use .format() syntax, for clarity.
Added some additional unit tests, primarily for testing dates like "nnn {units} ago", which are what I'm using the library to parse.
Reformatted many of the regexes for clarity. They now have consistent indentation.
All unit tests still pass, except for the `TestFrenchLocale.py` tests, which never worked on my computer (I have no locales installed at all - it's a server).