issue112: + add opened event emitter

src/app/material-timepicker/ngx-material-timepicker.component.spec.ts

@@ -98,11 +98,14 @@ describe('NgxMaterialTimepickerComponent', () => {
         expect(component.selectedPeriod).toBe(TimePeriod.AM);
     });
 
-    it(`should set isOpened 'true' and change animationState to 'enter' on open call`, () => {
+    it(`should set isOpened 'true', change animationState to 'enter' and emit event on open call`, async(() => {
+        let counter = 0;
+
+        component.opened.subscribe(() => expect(++counter).toBe(1));
         component.open();
         expect(component.isOpened).toBeTruthy();
         expect(component.animationState).toBe(AnimationState.ENTER);
-    });
+    }));
 
     it('should change animationState to \'leave\' on close call', () => {
         component.close();

src/app/material-timepicker/ngx-material-timepicker.component.ts

@@ -73,6 +73,7 @@ export class NgxMaterialTimepickerComponent implements OnInit, OnDestroy {
     }
 
     @Output() timeSet = new EventEmitter<string>();
+    @Output() opened = new EventEmitter<null>();
     @Output() closed = new EventEmitter<null>();
     @Output() hourSelected = new EventEmitter<number>();
 
@@ -163,6 +164,7 @@ export class NgxMaterialTimepickerComponent implements OnInit, OnDestroy {
     open(): void {
         this.isOpened = true;
         this.animationState = AnimationState.ENTER;
+        this.opened.next();
     }
 
     close(): void {