Auth_State: Add support for exception handling.
Auth_State: Add support for exception handling.

This patch introduces infrastructure for throwing exceptions within
authentication modules and processing filters, and later catching them
in the application which uses the filters.

ArtemTeleshev/php-saml2,madmatt/saml2,newmen/saml2,sgomez/saml2,simplesamlphp/saml2,sitya/saml2,cb8/saml2