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.
Always preserve the skeleton of the JSON files for translatable languages when importing translation jobs, even if it has empty nodes.
Added support for specifying the language in the optional options object when serializing.
Completed the unit tests module for the Java properties file parser module.
Changed the parser for CDATA sections of XML documents to no longer forgive a missing terminator character sequence.
Created unit tests for the CDATA section parser module.
Tweaks to titles of test cases.
Changed the parser for comment sections of XML documents to no longer forgive a missing terminator character sequence.
Created unit tests for the coment section parser module.
Created unit tests for the text node parser module.
Fixed a mixup in the test cases for the text parser module.
Fixed typo.
Changed the parser for tag attribute values of XML documents to no longer forgive a missing quote terminator character for quote-enclosed attribute values.
Created unit tests for the XML attribute value parser module.
Added a reset button to the shift-and-range widget.
Fixed a bug with the parser for XML tag attribute values, where bare values were not ever being terminated by ">" character that occurred before the first whitespace character.