[IMP] store: connect function takes hash function in param

With this commit, we can now decides precisely if a component should be
rerendered, by using a hash function.

By default, the hash function will deep observe each store element
coming from the result of the mapStateToProps.

closes #24

tests/utils.test.ts

@@ -5,6 +5,7 @@ import {
   memoize,
   debounce,
   findInTree,
+  shallowEqual,
   patch,
   unpatch
 } from "../src/utils";
@@ -94,6 +95,17 @@ describe("findInTree", () => {
   });
 });
 
+describe("shallowEqual", () => {
+  test("simple comparisons", () => {
+    const obj1 = {};
+    expect(shallowEqual(obj1, obj1)).toBe(true);
+    expect(shallowEqual({}, {})).toBe(true);
+    expect(shallowEqual({ a: 1 }, {})).toBe(false);
+    expect(shallowEqual({ a: 1 }, { a: 1 })).toBe(true);
+    expect(shallowEqual({ a: 1 }, ["a"])).toBe(false);
+  });
+});
+
 describe("patch/unpatch", () => {
   test("can monkey patch a class", () => {
     class Test {