[4.3.4] Spells/Mage: Ring of Frost

Ring of Frost (http://old.wowhead.com/spell=82676)

A little bit of explanations about how this scripts work.

Fist of all we have spell `SPELL_MAGE_RING_OF_FROST_FREEZE` (http://old.wowhead.com/spell=82676) wich freezes enemies at a given position. On the script for this spell we're only filtering targets acording to the "ring" structure.

Secondly we have the spell itself, the `SPELL_MAGE_RING_OF_FROST_SUMMON` (http://old.wowhead.com/spell=82676). This one have two effects: summon the RoF npc and a periodic effect. We're using the periodic efect for making the mage cast the previous spell (`SPELL_MAGE_RING_OF_FROST_FREEZE`) at the summoned npc position on every tick.

Finally `SPELL_MAGE_RING_OF_FROST_DUMMY` is an aura wich lasts 3 seconds and is used as coalesce pseudo-marker for the ring and for preventing players wich got dispeled the freeze effect again frozen.

http://www.wowwiki.com/Ring_of_Frost

--- 
```sql
DELETE FROM `spell_script_names` WHERE `spell_id` IN (82676, 82691);
INSERT INTO `spell_script_names`(`spell_id`, `ScriptName`) VALUES
(82676, 'spell_mage_ring_of_frost'),
(82691, 'spell_mage_ring_of_frost_freeze');

-- Set flags UNIT_FLAG_DISABLE_MOVE| UNIT_FLAG_STUNNED|UNIT_FLAG_NOT_SELECTABLE on Ring of Frost
UPDATE `creature_template` SET `unit_flags` = 0x4|0x40000|0x2000000 WHERE `entry` = 44199;
```