XmlArray: Parse an XML document into an array and vice-versa

This class can be used to parse an XML document into an array, and vice-versa, i.e. generate an array from a XML document.

It can parse a XML documents and build a nested associative array that associates XML document tags to tags and data contained.

The class can also do the opposite, i.e. take an associative array and generate a XML document from the array of definitions of tags and data.