Remove usage of lodash _.sortBy.

Relates to #68.

src/lang/lang_extensions.ts

@@ -63,10 +63,6 @@ namespace chevrotain.lang {
         containsKey(key:string):boolean {
             return utils.has(this._state, key)
         }
-
     }
 
 }
-
-
-

src/parse/gast_builder.ts

@@ -188,7 +188,7 @@ namespace chevrotain.gastBuilder {
                                                                                            topLevelRange:r.IRange,
                                                                                            allRanges:IProdRange[]):T {
         let secondLevelProds = getDirectlyContainedRanges(topLevelRange, allRanges)
-        let secondLevelInOrder = _.sortBy(secondLevelProds, (prodRng) => { return prodRng.range.start })
+        let secondLevelInOrder = utils.sortBy(secondLevelProds, (prodRng) => { return prodRng.range.start })
 
         let definition:gast.IProduction[] = []
         utils.forEach(secondLevelInOrder, (prodRng) => {

src/utils/utils.ts

@@ -234,4 +234,10 @@ namespace chevrotain.utils {
         }
         return -1
     }
+
+    export function sortBy<T>(arr:T[], orderFunc:(item:T) => number):T[] {
+        let result = cloneArr(arr)
+        result.sort((a, b) => orderFunc(a) - orderFunc(b))
+        return result
+    }
 }

test/utils/utils_spec.ts

@@ -162,5 +162,11 @@ namespace chevrotain.utils.spec {
             expect(indexOf([1, 2, 3], 0)).to.equal(-1)
             expect(indexOf([], -2)).to.equal(-1)
         })
+
+        it("exports a sortBy utility", () => {
+            expect(sortBy([1, 2, 3], (num) => num)).to.deep.equal([1, 2, 3])
+            expect(sortBy([3, 2, 1], (num) => num)).to.deep.equal([1, 2, 3])
+
+        })
     })
 }