Removed references to Java properties files, since this test module is for the PO file parser.
Created a generic abstract base class for parsing items lists, where subclasses can configure one or more item type parsers.
The items parser should stop parsing if it can't find a parsable item at the current position.
Fixed typo in test module.
Refactored the document parsers for XML documents and PO files to subclass the new items parser abstract base class.