Fixes the condition for symbols for completion engine.

Issue: #27
Removes IMemoryManager::registerExternalPointer and IMemoryManager::releaseExternalPointer.
Fixes GenerationalMemoryManager::moveYoungObjects.

Issue: #27
Removes unneeded volatile qualifiers.

Issue: #27
Prettifies BakerMemoryManager::releaseExternalHeapPointer.

Issue: #27