Fixing a error where I was not including all database column names in 'ItemDataSource'. Also improving comments.
Adding 'insertItem' method to 'ItemDataSource' class for adding new items to db and listView.
Fixing a bug where items were retrieved from the db and added twice to the listView.
Correcting a SQL syntax error in 'MySQLiteHelper'.
Tweaking the layout in 'activity_main' a bit. This will likely change.
Moving 'SelectionAdapter' class to its own file for clarity.