DB.insertNote() now correctly throws InvalidOperationException

As requested by the docstring, when adding a new Note to an Entry
that can't be updated
Fixed a bug in ListActivity

The ClickListener that checked if a Note can be modified didn't use the a real
(shared between activities) SharedPreferences file but the one provided by
Activity.getPreferences() that contains key/value only for the single Activity
DB.updateNote() now correctly throws InvalidOperationException

As requested by the docstring, when updating a Note that can't no
longer be modified
DB.deleteNote() now correctly throws InvalidOperationException

As requested by the docstring, when deleting a Note that can't no
longer be deleted
DB.setMood() now correctly uses InvalidOperationException

As required by the DBInterface documentation, when setting a Mood of an Entry
that can no longer be updated.
DB.removeMood() now correctly uses InvalidOperationException

As required by the DBInterface documentation, when removing the Mood of an Entry
that can no longer be updated.
DB.setPhoto now correctly uses InvalidOperationException

As requested by the DBInterface documentation, the method now throws
InvalidOperationException when setting the photo of an Entry that
can't no longer be updated
Refactor of DB.deletePhoto in DB.removePhoto

The new version has a different signature that requires the Entry with the Photo
to be removed instead of the Photo directly.
This way I can check if the Entry can be updated and its photo deleted.
Now this method also deletes the photo jpeg from external storage