Update strong ice wave.lua

Bug fix: http://otland.net/threads/best-released-real-map-10-31-based-1-0.204514/page-29#post-1986125 

Changed area from 4 to 5. 
Source: http://tibia.wikia.com/wiki/Strong_Ice_Wave
Reason: "This spell has the same cooldown, manacost and damage formula as the Sorcerer's Energy Wave."