made Stud.IP cache compatible with PSR-6, re #3701

app/controllers/admin/cache.php

app/controllers/file.php

composer.json

composer.lock

db/migrations/1.154_recalculate_score.php

db/migrations/1.224_db_cache_table.php

db/migrations/1.318_step_00353_cache.php

db/migrations/5.5.26_tic3193_no_unlimited_courses.php

db/migrations/6.0.3_adjust_cache_configuration.php

lib/activities/Activity.php

lib/bootstrap-autoload.php

lib/bootstrap-definitions.php

lib/bootstrap.php

lib/classes/MvvPerm.php

lib/classes/Score.class.php

lib/classes/SemClass.class.php

lib/classes/SemType.class.php

lib/classes/Seminar.class.php

lib/classes/SimpleORMap.class.php

lib/classes/Siteinfo.php