Optimized some slow parts of the engine.

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

app/imports/api/engine/computation/buildComputation/removeSchemaFields.js

@@ -3,17 +3,8 @@ import { unset } from 'lodash';
 
 export default function removeSchemaFields(schemas, prop){
   schemas.forEach(schema => {
-    schema._schemaKeys.forEach(key => {
-      // Skip object and array keys, except the errors array
-      if (
-        schema.getQuickTypeForKey(key) === 'object' ||
-        (
-          schema.getQuickTypeForKey(key) === 'objectArray' &&
-          key.slice(-6)!== 'errors'
-        )
-      ) return;
-      // Unset other computed only keys
-      applyFnToKey(prop, key, unset)
-    });
+    schema.removeBeforeComputeFields().forEach(
+      key => applyFnToKey(prop, key, unset)
+    );
   });
 }