XML: Parse XML documents into arrays and vice-versa

This class can be used to parse XML documents and build an array with the document structure.

It can also generate XML documents from nested arrays that define the document tag structure.

The class can load XML documents from files or text strings. It turns the document tags into keys of a nested associative array. The resulting array is stored in a class variable.

It can also take an array with the document structure and generate a XML document. The document XML is returned as a string.