Echoing Ooze / SummonCopySpell creates broken event triggers when the summon fails

[doctorpangloss]

SummonCopySpell should check if the summon was successful before adding all the triggers.

This causes Echoing Ooze's original copy to double up on all its triggers, because:

1. Minion clone = template.clone creates two entities with the same IDs.
2. The summon fails, because, e.g., you have 7 minions.
3. The triggers are added anyway. Since the clone has the same ID as the original Echoing Ooze, the triggers are still successfully added even though they're not really following the rules.