IRespawnInitiator and InventoryActions are abstract classes, but they
were missing a virtual destructor. Define it, even if it does nothing
and its absence most likely makes no difference other tha causing
warnings during compile.

Irrlicht 1.8 compat); also find dungeon master's fireball texture
again; add /spawnentity command

Make ToolItem and MaterialItem to convert names by aliases at creation time too (necessary for eg. crafting)