* Migrate email utils to non-static

* Migrate http utils to non-static

* Migrate net utils to non-static

* Migrate random utils to non-static

* Migrate system utils to non-static

* Migrate time utils to non-static

* Migrate xml utils to non-static

* Upgrade notes

* Update test-framework

* Fix tests

Convert to our wrapper class for assertions

* Migrate assertions to Webmozart

* 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

Fix Psalm-issues in the modules-directory

Because it's used in the _REQUEST array, the name is changed by PHP
to replacethe dot with an underscore, leading it not to match, that
in turn breaking the exception handling.

Thanks pverbaan for reporting this issue.

Closes: #1077

This reverts commit ef36c5fd.

All a bit too involved right before a planned release.

Also, convert to PSR-2 where that was still lacking in these files.

Working toward some of the requested tasks in
https://github.com/simplesamlphp/simplesamlphp/wiki/List-of-tasks

(being respectful with occurences that might change the behaviour, i.e. default database prefixes)

Refactor SimpleSAML_Auth_State::extractPersistentAuthState() to getPersistentAuthData() to avoid confusions around the behaviour of this method.

Move SimpleSAML_Auth_Default::extractPersistentAuthState() to SimpleSAML_Auth_State::extractPersistentAuthState() and deprecate the former.

Move SimpleSAML_Utilities::parseStateID() to SimpleSAML_Auth_State::parseStateID() and deprecate the former.

Move SimpleSAML_Utilities:: redirectUntrustedURL() to SimpleSAML\Utils\HTTP:: redirectUntrustedURL() and deprecate the former.

Move SimpleSAML_Utilities:: redirectTrustedURL() to SimpleSAML\Utils\HTTP:: redirectTrustedURL() and deprecate the former.

Move SimpleSAML_Utilities::generateID() to SimpleSAML_Utils_Random::generateID(). Deprecate the former and schedule it for removal in 2.0.

Solve a security issue with some modules (not validating URLs we are redirecting to) by moving the check to the SimpleSAML_Auth_State::loadState() method.