Inform

- Strip out empty culprits and codicils.

- Added *clone* argument to *InformantFactory*.

- Allow *ProgressBar* output to be suppressed.
- Allow ``/`` to be overridden in *plural*.
- Various enhancements to *conjoin* and *full_stop*.
- Added *parse_range* and *format_range* functions.
- Added *title_case* function.

- Add *format* method to *inform.plural*

Minor fixes.

- Wrap now applies to codicils passed as arguments.
- Enhance inform.plural (now supports pluralizing verbs).
- Add fmt argument to inform.conjoin()
- Support template attribute on subclasses of inform.Error