[PageFlow] introduced the PageFlowRegistries class to handle multiple registries
[Continuation] renamed the class GC to GarbageCollector
[Continuation] renamed the argument of the GarbageCollector::sweep() method
[Continuation] renamed the second argument of the GarbageCollector::__construct() method
[Continuation] renamed the property ContinuationServer::$gc to $garbageCollector
[Continuation] added missing PHPDoc to the ContinuationServer class
[Continuation] moved the class GarbageCollector into the namespace Piece\Flow\Continuation\GarbageCollection
[Continuation] moved the class Clock into the namespace Piece\Flow\Continuation\GarbageCollection
[Continuation] introduced the GarbageMarker class
[Continuation] renamed the property GarbageCollector::$markers to $garbageMarkers
[Continuation] renamed the method GarbageCollector::isMarked() to shouldSweep()
[Continuation] improved the GarbageCollector::mark() and sweep() methods
[Continuation] introduced the GarbageMarker::isExpired() method
[Continuation] removed the GarbageMarker::getModificationTimestamp() method