Use typehint instead of assert for Authproc and auth source methods.

lib/SimpleSAML/Auth/ProcessingChain.php

lib/SimpleSAML/Auth/ProcessingFilter.php

lib/SimpleSAML/Auth/Simple.php

lib/SimpleSAML/Auth/Source.php

lib/SimpleSAML/Auth/State.php

modules/authX509/lib/Auth/Process/ExpiryWarning.php

modules/authX509/lib/Auth/Source/X509userCert.php

modules/authYubiKey/lib/Auth/Source/YubiKey.php

modules/authcrypt/lib/Auth/Source/Hash.php

modules/authcrypt/lib/Auth/Source/Htpasswd.php

modules/authfacebook/lib/Auth/Source/Facebook.php

modules/authlinkedin/lib/Auth/Source/LinkedIn.php

modules/authorize/lib/Auth/Process/Authorize.php

modules/authtwitter/lib/Auth/Source/Twitter.php

modules/authwindowslive/lib/Auth/Source/LiveID.php

modules/cas/lib/Auth/Source/CAS.php

modules/cdc/lib/Auth/Process/CDC.php

modules/consent/lib/Auth/Process/Consent.php

modules/core/lib/Auth/Process/AttributeAdd.php

modules/core/lib/Auth/Process/AttributeAlter.php