Closes #604

Remove identifier from VirtualPropertyManager
Add VirtualPropertyManager to the query of allProperties

src/engine/openspaceengine.cpp

@@ -178,6 +178,10 @@ OpenSpaceEngine::OpenSpaceEngine(std::string programName,
     _rootPropertyOwner->addPropertySubOwner(_renderEngine.get());
     _rootPropertyOwner->addPropertySubOwner(_renderEngine->screenSpaceOwner());
 
+    // The virtual property manager is not part of the rootProperty owner since it cannot
+    // have an identifier or the "regex as identifier" trick would not work
+    //_rootPropertyOwner->addPropertySubOwner(_virtualPropertyManager.get());
+
     if (_windowWrapper) {
         _rootPropertyOwner->addPropertySubOwner(_windowWrapper.get());
     }

src/engine/virtualpropertymanager.cpp

@@ -28,8 +28,12 @@
 
 namespace openspace {
 
+// The VirtualPropertyManager cannot have an identifier (and thus cannot be part of
+// another PropertyOwner) as otherwise the regex-as-name trick would no longer work. I
+// don't particular like this implementation, but it's what we got for now;  I'm open to
+// replacing it with a better mechanism
 VirtualPropertyManager::VirtualPropertyManager()
-    : properties::PropertyOwner({ "VirtualPropertyManager" })
+    : properties::PropertyOwner({ "" })
 {}
 
 void VirtualPropertyManager::addProperty(std::unique_ptr<properties::Property> prop) {