Virulent Disease now tries to choose smartly which disease to apply (one that is not on the targe yet and that will reduce a stat that is high. So an 
archer type target will always ge the dex disease first).
Virulentt Disease damage & stat reducion buffed
Darkfire cost and cooldown reduced
Many corruption spells are now able to crit, including diseases.


git-svn-id: http://svn.net-core.org/repos/t-engine4@5036 51575b47-30f0-44d4-a5cc-537603b46e54