Library for parsing ISO 8601 strings

Features
* Pure Python implementation
* Python 3 support
* Logical behavior
  - Parse a time, get a datetime.time
  - Parse a date, get a datetime.date
  - Parse a datetime, get a datetime.datetime
  - Parse a duration, get a datetime.timedelta
  - Parse an interval, get a tuple of dates or datetimes
  - Parse a repeating interval, get a date or datetime generator
* UTC offset represented as fixed-offset tzinfo
* Parser separate from representation, allowing parsing to different datetime
  formats
* No regular expressions