Merge pull request #405 from TalkTakesTime/master

Treat Mega formes as Gen 6 mons
Gen 4: Fix Hidden Power base powers
Merge pull request #407 from ALAKTORN/patch-12

Gen 4: Fix Hidden Power base powers
Add new item: Snowball
Arceus-Fairy can only be used in Gen 6
Add complete Xerneas learnset
Update Dedenne learnset

Complete, excluding egg moves
Update Carbink learnset

Complete, excluding egg moves
Update Klefki learnset

Complete, excluding egg moves
Implement Venom Drench
Infestation makes contact
Implement Belch
Merge pull request #412 from ALAKTORN/patch-6

Infestation makes contact
Updated learnsets for bergmite-zygarde
Done by Smogon Research, typed up by jas61292
Add new item: Luminous Moss
Add new item: Roseli Berry
Update Xerneas/Zygarde learnsets

- Xerneas learns Nature Power at level 72
- Zygarde learns Dragon Dance at level 72
Add new event Pokemon
Implement new item: Weakness Policy

Note: unsure if single use
Implement mega evolution