ChecklistActivity: Add javadoc for some class fields and change TODO comment for method refreshChecklistDataAndView()
ItemDescriptionEntryActivity: Add javadoc for some fields
ItemDescriptionEntryActivity.fetchChecklistItemDescriptionFromDatabase: Check itemId before using it
ItemDescriptionEntryActivity.fetchChecklistItemDescriptionFromDatabase: Change TODO
ItemsDbHelper: Declare some of the local variables and parameters as final
ItemsDbHelper: Correct javadoc
ItemsDbHelper: Add javadoc for all of the public methods
ItemsDbHelper: Declare some of the local variables and parameters as final
ItemsDbHelper: Methods checkAllItems() and uncheckAllItems() use almost the same code, so move the common code into another method and call it with the appropriate value.