Fixes and enhancements
* Add `functions multimedia.image.PIL.{apply,get}_orientation`
* Add constant `ORIENTATION_TO_ROTATION` to `multimedia.exif.image.Image`
* Make function `multimedia.image.PIL.apply_orientation` more generic
* Make function `multimedia.image.PIL.apply_orientation` defaulting to nothing if orientation is crazy
* Make function `multimedia.image.PIL.get_orientation` more robust
* Class `exceptions.MessageMixin`: Fix pickle recursion error
Features
* Add module `multimedia.image.PIL`
* Add function `types.merge_base_attribute`