Optimized some slow parts of the engine.

Last low hanging fruit: parsing is slow, cache parsed calculations

app/imports/api/engine/computation/computeComputation/computeByType/computeVariable/computeImplicitVariable.js

@@ -7,9 +7,12 @@ import getAggregatorResult from './getAggregatorResult.js';
  export default function computeImplicitVariable(node){
    const prop = {};
    const result = getAggregatorResult(node);
-   prop.total = result;
-   prop.value = result;
-   prop.proficiency = node.data.proficiency;
+   if (result !== undefined){
+     prop.value = result;
+   }
+   if (node.data.proficiency !== undefined){
+     prop.proficiency = node.data.proficiency;
+   }
 
    // denormalise class level aggregator
    let classLevelAgg = node.data.classLevelAggregator;

app/imports/api/engine/computation/computeComputation/computeCalculations.js

@@ -35,6 +35,7 @@ function evaluateCalculation(calculation, scope){
   // remove the working fields
   delete calculation._parseLevel;
   delete calculation._parsedCalculation;
+  delete calculation._localScope;
 }
 
 function embedInlineCalculations(inlineCalcObj){