Adds effects and begins using them for digestion
Composition no longer requires that internal mechanics obey :mutable, but keeps :mutable around for checking when players / NPCs are allowed to move objects from one place to another simply; modifies Position to be cleaner and more uniformly applied throughout the codebase; fixes some bugs in EffectTarget
Merge branch 'master' of github.com:datalurkur/Bushido-Mongers