Renamed propertyTitle to Key in Page entity; added property to map

Author: mechelon

src/Entities/Page.php

@@ -156,10 +156,11 @@ private function fillTitle(): void
  * @param $property
  * @return Page
  */
- public function set(string $propertyTitle, Property $property): Page
+ public function set(string $propertyKey, Property $property): Page
  {
- $property->setTitle($propertyTitle);
+ $property->setTitle($propertyKey);
  $this->properties->add($property);
+ $this->propertyMap[$propertyKey] = $property;
 
  if ($property instanceof Title) {
  $this->title = $property->getPlainText();