Add support for converting and rendering volumetric data in the cdf format. Replace DataConverter by a more general purpose TaskRunner.

Conflicts:
	modules/volume/CMakeLists.txt
	modules/volume/linearlrucache.h
	src/engine/openspaceengine.cpp

src/engine/openspaceengine.cpp

@@ -50,6 +50,7 @@
 #include <openspace/scene/translation.h>
 #include <openspace/scene/scene.h>
 #include <openspace/util/factorymanager.h>
+#include <openspace/util/task.h>
 #include <openspace/util/time.h>
 #include <openspace/util/timemanager.h>
 #include <openspace/util/spicemanager.h>
@@ -165,6 +166,10 @@ OpenSpaceEngine::OpenSpaceEngine(std::string programName,
         std::make_unique<ghoul::TemplateFactory<Scale>>(),
         "Scale"
     );
+    FactoryManager::ref().addFactory(
+        std::make_unique<ghoul::TemplateFactory<Task>>(),
+        "Task"
+    );
 
     SpiceManager::initialize();
     Time::initialize();