Modifications to make phpxmlrpc work with modern PHP

There is some fixes and also some deprecated code removed, that was not anymore used for anything.

Main payload is though converting $GLOBALS array usage to internal class, which avoid pollution of global namespace and also allows usage of phpxmlrpc with project that also touches $GLOBALS in bad way.

My personal problem with it was that PHPUnit wanted to clear $GLOBALS after every test, so I saw better just fix this project rather than messing with PHPUnit regarding that.