This goes through nearly all the Subversion client code, ensuring

function signatures, lists, and dictionaries all have types defined.
This has helped uncover many cases where we were assuming values were

not None or assuming values were the right type (such as a string

instead of an integer).
Logic has been rewritten in some cases to aid in type safety, such as

when building a diff and dealing with a mixture of lists and generators.

Unit tests pass.