[Shotwell] trashing RAW+JPEG pairs and option watch library directory for new files

[Maximilian B]

I think there is a minor bug in 0.11:

1. enable watch library directory for new files
2. set RAW developer default to camera
3. import paired RAW+JPEG
4. press DEL key to trash a paired photo
5. close an restart shotwell
6. trashed RAW will appear in trash, JPEG will be discovered and a new
event will be created containing that JPEG
(7. empty trash will remove both files from library and filesystem)

btw, thank you very much for the new raw support. looking forward for 0.12.

best