Code review change: split tassign into its own package.

[fixes angular-redux#216]

Author: Seth Davenport

docs/strongly-typed-reducers.md

@@ -148,7 +148,7 @@ Instead, we've provided a type-corrected immutable assignment function, `tassign
 that will catch this type of error:
 
 ```typescript
-import { tassign } from 'ng2-redux';
+import { tassign } from 'tassign';
 
 export const barReducer: Reducer<IBar> = (state: IBar, action: Action<number | string>): IBar => {
   switch(action.type) {

examples/counter/package.json

@@ -32,10 +32,11 @@
     "core-js": "^2.3.0",
     "ng2-redux": "^4.0.0-beta.7",
     "redux": "^3.5.0",
-    "redux-logger": "^2.6.1",
     "redux-localstorage": "^0.4.0",
+    "redux-logger": "^2.6.1",
     "reflect-metadata": "0.1.3",
     "rxjs": "5.0.0-beta.12",
+    "tassign": "^1.0.0",
     "zone.js": "^0.6.21"
   },
   "devDependencies": {

examples/counter/store/search.reducer.ts

@@ -1,3 +1,4 @@
+import { tassign } from 'tassign';
 import { SEARCH_ACTIONS } from '../actions/search.actions';
 
 export interface ISearchState {
@@ -18,14 +19,14 @@ export function searchReducer(
 
   switch (action.type) {
     case SEARCH_ACTIONS.SEARCH:
-      return Object.assign({}, state, {
+      return tassign(state, {
         onSearch: true,
         keyword: action.payload,
         total: state.total
       });
     case SEARCH_ACTIONS.SEARCH_RESULT:
       let total = action.payload.total;
-      return Object.assign({}, state, {
+      return tassign(state, {
         onSearch: state.onSearch,
         keyword: state.keyword,
         total