Defcon

- When calculating area, auto close pen (this is somewhat controversial, and may change in the future)
- Provides identifier for the transformPointPen
- Improve debugging of held notifications
- Add validation support (see validation options in UFOLib)
- Update methods for UFOLib 2.3.1

- No longer stores representations in objects without a dispatcher.

- Added kerning.find() method, to find a value for a pair, even if the pair is not specifically defined in the kerning; i.e., the method is given a glyph name that has kerning, but only because it is in a kerning group.

- When saving a new font created from scratch, or one loaded from a different path, to the location of another existing UFO, the latter is automatically overwritten with the new one (180).
- When saving a font in-place and the existing UFO is invalid, overwrite the latter (165, 180).
- Allow to rename the default layer when saving in-place (165, 180).