This reverts commit dabe7e47.

Now also considers any attributes.po in the configured theme, if any.
Makes the attributes.extradictionary config setting obsolete.

We could use it everywhere, but it's better to reduce the already big
amount of configuration options the admin is confronted with than the
small problem this option solves.

Co-authored-by: Tim van Dijen <tim.dijen@minbzk.nl>

Convert to our wrapper class for assertions

Fix Locale; If a Twig-variable is not set and then translated, these methods are called with a null parameter

* Remove deprecated classes

* Remove support for certificate fingerprints

* Remove many deprecated methods and pieces of code

* Remove SAML1.1/Shib1.3 support

* Remove many superfluous annotations

* Update unit test to work with new PHPunit

Closes #1268 
Closes #1020 
Closes #431 
Closes #167 
Closes #151 

* Migrate assertions to Webmozart

* Use strict variables in Twig, except for our TemplateTest; throw exception on missing variables

* Fix issues due to Twig strict_variables=true

* Fix for #1229

* Fix metadata-template

* Raise minimum PHP version to 7.0

* Remove tests pre-PHP 7.2

* Upgrade dev dependencies

* Ignore tests for deprecated class

* Add typehints; not touching public API

* Remove none-array replacements-param; old behaviour from pre-1.4 release

* Psalm fixes

* Add upgrade notes

* PSR-12

PSR-12 compliancy

* Ensure getConfig* functions can only return Configuration

* Cleanup after #1189

* Deprecate Configuration::getConfigList

The OASIS spec [SAML V2.0 Subject Identifier Attributes Profile](https://wiki.oasis-open.org/security/SAMLSubjectIDAttr) defines two new standard attributes intending to replace use of persistent NameIDs and the eduPersonTargetedID and eduPersonUniqueId SAML attributes. The updated Kantara [SAML V2.0 Interoperability Deployment Profile](https://kantarainitiative.github.io/SAMLprofiles/saml2int.html) will also standardize on these new attributes (cf. SDP-SP15 ibid.).

This commit adds the two new attributes:

* to the URN attribute maps
* to attribute definitions and translations of the locale system
* to the smartattributes:SmartID auth proc filter (after any other SAML attributes, but before the non-SAML ones).

Support for saml2int SDP-SP16 (attribute requirements signalling via Entity Attributes) is not included here.