no mana requirements for D2RMM

Removes the mana requirements from skills.

For some reason, i guess it's hardcoded, some skills still require the character to have a minimum of mana to cast the skill, though the mana won't be consumed. The skills in question are Inferno, Arctic Blast and Blade Fury.  I set the field to 0 on the mod, but still a small amount of mana is required (at least on the description of the skill). It's 4 for Inferno and Arctic Blast and 3 for Blade Fury. The mana required is small, so unless Baal drains all your mana, it won't be noticeable when using these 3 skills. In the original file the mod modifies, this field is set to 6 mana for all 3 skills.