Removes a single resource, meaning it will be removed from the list of valid resources in this manager, also causing it to be unloaded. The word 'Destroy' is not used here, since if any other pointers are referring to this resource, it will persist until they have finished with it; however to all intents and purposes it no longer exists and will likely get destroyed imminently. If you do have references to resources hanging around after the ResourceManager is destroyed, you may get problems on destruction of these resources if they were relying on the manager (especially if it is a plugin). If you find you get problems on shutdown in the destruction of resources, try making sure you release all your references before you shutdown OGRE.
