DecisionTreeTest: Fix the build.
ItemsContentProvider: Add a comment about how the server doesn't fail on bad credentials.

It would be nice if it did.
LoginActvity: Try to stop autocorrections in the username.

Apparently this is the most reliable way to do this, though even
then it depends on the (bugs of the) input method being used.
QuestionHelpFragment: Really add space between the example thumbnails.
ItemsContentProvider.getIntPref(): Avoid an exception when the preference is empty.
Remove some unused commented-out code.
LoginActvity, ItemsContentProvider: Store the login details in the AccountManager.

Instead of in SharedPreferences.
Add accounts permissions.

Otherwise we are not allowed to get our own account details and our own
credentials from that account.
Authenticator: Implement addAccount() so the user can add an account via Settings.