Increase improvement rates for attack spells.

Forum thread: http://openmeridian.org/forums/index.php/topic,339.0.html

Current rates:

    Blast of fire:    viChance_To_Increase = 5
    Explosive frost:    viChance_To_Increase = 5
    Illusionary wounds:    viChance_To_Increase = 10 (uses atakspel.kod)
    Shocking fury:    viChance_To_Increase = 5
    Splash of acid:    viChance_To_Increase = 5
    Vampiric drain:    viChance_To_Increase = 10
    Fireball:    viChance_To_Increase = 7 (boltspel.kod)
    Lightning bolt:    viChance_To_Increase = 7 (boltspel.kod)
    Earthquake:    viChance_to_increase = 10
    Ice Nova:    viChance_to_increase = 15 (not available yet)

Suggested rates:

    Blast of fire:    viChance_To_Increase = 15
    Explosive frost:    viChance_To_Increase = 15
    Illusionary wounds:    viChance_To_Increase = 20 (uses atakspel.kod)
    Shocking fury:    viChance_To_Increase = 20
    Splash of acid:    viChance_To_Increase = 15
    Vampiric drain:    viChance_To_Increase = 20
    Fireball:    viChance_To_Increase = 20 (boltspel.kod)
    Lightning bolt:    viChance_To_Increase = 15
    Earthquake:    viChance_to_increase = 15
    Ice Nova:    viChance_to_increase = 15 (not available yet)