- Added username, password arguments.
  - Documented existing revision argument.
  - Corrected documentation/docstrings; removed git references, use svn
    nomenclature, etc.
  - Refactored duplicate code, redundant shell calls, filter abuse,
    inconsistent formating, etc.
  - Shell quoting so it doesn't break for one guy who has spaces in
    pathnames.
  - svn called with '--non-interactive' and '--no-auth-cache'.