Add methods to get effective Item or Ability
pokemon.hasItem and pokemon.hasAbility account for Gastro Acid, Klutz, Magic Room and Embargo
Fix ignoring abilities or items sometimes being not effective
Items: Light Clay, Metronome
Abilities: Aura Break, Contrary, Gluttony, Levitate, Mega Launcher, Minus, Mold Breaker, Persistent, Plus, Shadow Tag, Slow Start, Soundproof, Stall, Unburden, Teravolt, Turboblaze, Zen Mode
Fix 2-turn moves ignoring No Guard
Merge pull request #832 from Slayer95/master

Fixes for Embargo, Gastro Acid, Klutz, Magic Room and No Guard