------------------------
Adds the following functions and classes:
* pockets.collections.groupify
* pockets.collections.keydefaultdict
* pockets.collections.nesteddefaultdict
* pockets.collections.readable_join
* pockets.datetime.ceil_datetime
* pockets.datetime.floor_datetime
* pockets.datetime.round_datetime
* pockets.datetime.timedelta_total_seconds
* pockets.decorators.argmod
* pockets.inspect.unwrap
* pockets.string.fieldify
* pockets.string.unfieldify
* pockets.string.slug
Additionally renames the following classes (the original names
are still exported for backwards compatibility):
* pockets.iterators.modify_iter -> itermod
* pockets.iterators.peek_iter -> iterpeek