Re #11 - Documentation * Document Stats and SystemStats at class level to explain the difference * Document WarFoundryXmlFactory at class level Re #13 - XPath for XML loading * Load categories using XPath - needs fixing so we can do a proper "categories/cat" query Re #10 - Refactoring for readability * Fix method signature for getting number from attribute added in r19 * Refactor more code in to GetExtraData method * Separate out loading of categories for GameSystem