feat(loki): add 'dataOptions' to eqJoin (#33)

Add additional 'dataOptions' parameter to Resultset eqjoin and transform eqJoin step operations to allow removing meta from both left and right sides. This is meant for easier grafting into single object to be inserted into the eqJoin (temporary) collection.
(from techfort/LokiJS#618)

Author: Viatorus

packages/loki/src/resultset.js

@@ -445,7 +445,7 @@ export class Resultset {
           rs = rs.map(step.value);
           break;
         case "eqJoin":
-          rs = rs.eqJoin(step.joinData, step.leftJoinKey, step.rightJoinKey, step.mapFun);
+          rs = rs.eqJoin(step.joinData, step.leftJoinKey, step.rightJoinKey, step.mapFun, step.dataOptions);
           break;
         // following cases break chain by returning array data so make any of these last in transform steps
         case "mapReduce":
@@ -1125,13 +1125,14 @@ export class Resultset {
   /**
    * eqJoin() - Left joining two sets of data. Join keys can be defined or calculated properties
    * eqJoin expects the right join key values to be unique.  Otherwise left data will be joined on the last joinData object with that key
-   * @param {Array} joinData - Data array to join to.
+   * @param {Array|Resultset|Collection} joinData - Data array to join to.
    * @param {(string|function)} leftJoinKey - Property name in this result set to join on or a function to produce a value to join on
    * @param {(string|function)} rightJoinKey - Property name in the joinData to join on or a function to produce a value to join on
    * @param {function} [mapFun=] - a function that receives each matching pair and maps them into output objects - function(left,right){return joinedObject}
+   * @param {object} dataOptions - optional options to apply to data() calls for left and right sides
    * @returns {Resultset} A resultset with data in the format [{left: leftObj, right: rightObj}]
    */
-  eqJoin(joinData, leftJoinKey, rightJoinKey, mapFun) {
+  eqJoin(joinData, leftJoinKey, rightJoinKey, mapFun, dataOptions) {
     let leftData = [];
     let leftDataLength;
     let rightData = [];
@@ -1143,12 +1144,14 @@ export class Resultset {
     let joinMap = {};
 
     //get the left data
-    leftData = this.data();
+    leftData = this.data(dataOptions);
     leftDataLength = leftData.length;
 
     //get the right data
-    if (joinData instanceof Resultset) {
-      rightData = joinData.data();
+    if (joinData instanceof Collection) {
+      rightData = joinData.chain().data(dataOptions);
+    } else if (joinData instanceof Resultset) {
+      rightData = joinData.data(dataOptions);
     } else if (Array.isArray(joinData)) {
       rightData = joinData;
     } else {