Use the latest version of PHP-Parser

Previously, 0.9 was used.

Main changes:
- folder PHPParser moved to PhpParser
- PhpParser contains namespaces
- Rascal visitor generators are updated (the code is generated with the files)
- AST2Rascal class is moved to RascalPrinter
- AST2Rascal now only contains stuff to call RascalPrinter
- Generated tests are added (based on the previous version of the parser)