[IMP] observer: add set and delete static functions

This rev. add a 'set' and 'delete' static functions to the Observer.
They allow to set or delete (only for objects) properties on
observed objects or arrays.

With this, the 'set' functions in Store and Component are no longer
necessary, so they have been removed.

Closes #138

tests/observer.test.ts

@@ -134,6 +134,57 @@ describe("observer", () => {
     expect(arr[0].__owl__.rev).toBe(3);
   });
 
+  test("set new property on observed object", async () => {
+    const observer = new Observer();
+    observer.notifyCB = jest.fn();
+    const state: any = { a: 1 };
+    observer.observe(state);
+    expect(state.__owl__.rev).toBe(1);
+    expect(observer.rev).toBe(1);
+    expect(observer.notifyCB).toBeCalledTimes(0);
+
+    Observer.set(state, "b", 8);
+    await nextMicroTick();
+    expect(state.__owl__.rev).toBe(2);
+    expect(observer.rev).toBe(2);
+    expect(observer.notifyCB).toBeCalledTimes(1);
+    expect(state.b).toBe(8);
+  });
+
+  test("delete property from observed object", async () => {
+    const observer = new Observer();
+    observer.notifyCB = jest.fn();
+    const state: any = { a: 1, b: 8 };
+    observer.observe(state);
+    expect(state.__owl__.rev).toBe(1);
+    expect(observer.rev).toBe(1);
+    expect(observer.notifyCB).toBeCalledTimes(0);
+
+    Observer.delete(state, "b");
+    await nextMicroTick();
+    expect(state.__owl__.rev).toBe(2);
+    expect(observer.rev).toBe(2);
+    expect(observer.notifyCB).toBeCalledTimes(1);
+    expect(state).toEqual({ a: 1 });
+  });
+
+  test("set element in observed array", async () => {
+    const observer = new Observer();
+    observer.notifyCB = jest.fn();
+    const state: any = ["a"];
+    observer.observe(state);
+    expect(state.__owl__.rev).toBe(1);
+    expect(observer.rev).toBe(1);
+    expect(observer.notifyCB).toBeCalledTimes(0);
+
+    Observer.set(state, 1, "b");
+    await nextMicroTick();
+    expect(state.__owl__.rev).toBe(2);
+    expect(observer.rev).toBe(2);
+    expect(observer.notifyCB).toBeCalledTimes(1);
+    expect(state).toEqual(["a", "b"]);
+  });
+
   test("properly observe arrays in object", () => {
     const observer = new Observer();
     const state: any = { arr: [] };

tests/store.test.ts

@@ -152,24 +152,6 @@ describe("basic use", () => {
     store.dispatch("someaction");
   });
 
-  test("set function is given to mutations", async () => {
-    let updateCounter = 0;
-    const state = { bertinchamps: "brune" };
-    const mutations = {
-      addInfo({ state, set }) {
-        set(state, "chouffe", "blonde");
-      }
-    };
-    const store = new Store({ state, mutations, actions: {} });
-    store.on("update", null, () => updateCounter++);
-
-    expect(updateCounter).toBe(0);
-    store.commit("addInfo");
-    await nextMicroTick();
-    expect(updateCounter).toBe(1);
-    expect(store.state).toEqual({ bertinchamps: "brune", chouffe: "blonde" });
-  });
-
   test("can have getters from store", async () => {
     const state = {
       beers: {