Add functions to get the effect affecting resistance and weakness for another effect
Move code for listing effect sources to the spell management classes
Fix uninitialized mSkill/mAttribute for spellmaker spells
Don't advance acrobatics skill for NPCs
Implement Resist & Weakness effects
Implement damage tick effects
Implement RestoreHealth/Magicka/Fatigue
Merge remote-tracking branch 'scrawl/master'