[FIX] web_calendar: Destroy m2o when events are reloaded

when mode is switched m2o should be reinitialized, and old instance of
field manager should be destroyed otherwise it will through traceback
'cannot call methods on autocomplete prior to initialization', also
improved the reload_favorite_list, it should be called when
calendar.contacts record is created

addons/calendar/static/src/js/base_calendar.js

@@ -86,10 +86,24 @@ CalendarView.include({
 });
 
 widgets.SidebarFilter.include({
+    events_loaded: function() {
+        this._super.apply(this, arguments);
+        this.reinitialize_m2o();
+    },
     add_favorite_calendar: function() {
-        var self = this;
         if (this.dfm)
             return;
+        this.initialize_m2o();
+    },
+    reinitialize_m2o: function() {
+        if (this.dfm) {
+            this.dfm.destroy();
+            this.dfm = undefined;
+        }
+        this.initialize_m2o();
+    },
+    initialize_m2o: function() {
+        var self = this;
         this.dfm = new form_common.DefaultFieldManager(self);
         this.dfm.extend_field_desc({
             partner_id: {
@@ -113,6 +127,7 @@ widgets.SidebarFilter.include({
     },
     add_filter: function() {
         var self = this;
+        var defs = [];
         new Model("res.users")
         .query(["partner_id"])
         .filter([["id", "=",this.view.dataset.context.uid]])
@@ -121,11 +136,13 @@ widgets.SidebarFilter.include({
             $.map(self.ir_model_m2o.display_value, function(element,index) {
                 if (result.partner_id[0] != index){
                     self.ds_message = new data.DataSetSearch(self, 'calendar.contacts');
-                    self.ds_message.call("create", [{'partner_id': index}]);
+                    defs.push(self.ds_message.call("create", [{'partner_id': index}]));
                 }
             });
         });
-        reload_favorite_list(this);
+        $.when.apply(null, defs).done(function() {
+            reload_favorite_list(self);
+        });
     },
     destroy_filter: function(e) {
         var self = this;