Calculate timers for SPELL_SUMMON

[ntowle]

No description provided.

[ntowle]

["SPELL_SUMMON"] = {
    "Summon-259209-npc:122967-000019DF4E = pull:9.0, 34.3, 35.2, 35.2", -- [1]
},

Sometimes there are no other corresponding events with calculated timers, as is the case with 259209.

[MysticalOS]

+1 for this being merged.

A note to add, When I asked blizzard for an event for tentacle spawns on volocross, the event they chose was SPELL_SUMMON. So the case that spell summon is used in absence of a cast event isn't always the case. It may very well be the only cast event blizzard will use/add in some cases.