Update static_vars.lua

Add new color category to array: mobspellcol. Spell colors for players and NPC will have separate setting.
Update event_action.lua

Replaced spell color handler line to differentiate colors of PC and NPC casted spells.
Update colors.xml

New option added for setting color of spells casted by NPC: <mobspellcol>0</mobspellcol>. Color of spells casted by PC is still handled by <spellcol>0</spellcol>, just as before.
Update event_action.lua

Pulled nil out of color_it as per collaborator recommendation for player/NPC magic and weaponskills.
Merge pull request #366 from Zireael/master

Add color setting for NPC magic casting (enemies, automatons)