Moved creature variables to their own collection

Another big change to the engine, expect bugs

app/imports/api/engine/computation/CreatureComputation.js

@@ -2,7 +2,7 @@ import { EJSON } from 'meteor/ejson';
 import createGraph from 'ngraph.graph';
 
 export default class CreatureComputation {
-  constructor(properties, creature){
+  constructor(properties, creature, variables){
     // Set up fields
     this.originalPropsById =  {};
     this.propsById =  {};
@@ -12,6 +12,7 @@ export default class CreatureComputation {
     this.dependencyGraph = createGraph();
     this.errors = [];
     this.creature = creature;
+    this.variables = variables;
 
     // Store properties for easy access later
     properties.forEach(prop => {