Remove a now-unused method.
ItemsContentProvider.CreatedFileUri: Remove an unused member field.
ClassifyActivity: Don't implement ItemFragment.Callbacks because the superclass does.
Item: Make the *_DOWNLOADED column names the same as the internal names.

Though this should not be necessary.
Remove incorrect comments.
ItemsContentProvider: Correct a SQL column name.
.iml file changes for FindBugs.
Improve some Log messages.
UiUtils: Move error messages to strings.xml so we can translate them.
SubjectFragment: showImage(): Add a check for no item.
SubjectFragment, ListCursorAdapter: Abandon a subject if we cannot load one of its images.
SubjectFragment: Fix a typo in a null/empty check.
ItemsContentProvider: When getting the next item, check all images are downloaded.

This should prevent us from trying to show images that are not downloaded, though
that is fairly theoretical anyway.
ItemsContentProvider: Add comments about reusing old cache files.

Though this only happens when doing hacky things while debugging.
Remove unnecessary imports.
QuestionFragment.saveClassification(): Prevent saving with the 'next' ID.

Though it should never get this far anyway.
ClassifyFragment: remove a now-irrelevant comment.
ClassifyFragment: Really don't show UI when there is no next item.
ClassifyFragment: Warn when there is no next item.
strings.xml: Add a full stop (period) at end of messages.

I prefer it. I can't find any specific Android design guideline about it.