Update scoreboard.lua

These changes use the change I submitted to the actions.lua file. It will not work without that submission.

Created function FindPetOwnerName with logic to associate pet with owner. Any actions that can be done by a pet now use CreatePlayerName(action) instead of action:get_actor_name()

In spell_finish I changed the id 265 to 264. 264 was the message I was getting on sub targets when casting AoE black magic. This should fix the issue where AoE magic damage was not being processed (at least for black magic, I think pet AoE is still incorrect)
Having this default to nil seems slightly more reliable (and having line 500 check nil instead) so that you can determine success/failure based on type rather than value.