SimpleSAML_XML_* classes refactorized to PSR-4

lib/SimpleSAML/Bindings/Shib13/HTTPPost.php

lib/SimpleSAML/Utilities.php

lib/SimpleSAML/Utils/XML.php

lib/SimpleSAML/XML/Errors.php

lib/SimpleSAML/XML/Parser.php

lib/SimpleSAML/XML/Shib13/AuthnRequest.php

lib/SimpleSAML/XML/Shib13/AuthnResponse.php

lib/SimpleSAML/XML/Signer.php

lib/SimpleSAML/XML/Validator.php

modules/saml/lib/Auth/Source/SP.php

modules/saml/lib/IdP/SAML1.php

modules/saml/www/sp/saml1-acs.php

tests/lib/SimpleSAML/XML/ErrorsTest.php

tests/lib/SimpleSAML/XML/ParserTest.php

tests/lib/SimpleSAML/XML/Shib13/AuthnResponseTest.php