Registering a type now rebuilds it out of memory owned by the manager.

* Added TypeManager::RebuildType
 * rebuilds the type and its constituent types in terms of memory owned
 by the manager.
 * Used by TypeManager::RegisterType to properly allocate memory
* Adding an unit test to expose the issue
* Added some tests to provide coverage of RebuildType
* Added an accessor to the target pointer for a forward pointer