Open New Project-> Choose SharePoint Add-In or App for SharePoint Template
Then provide Office 365 credentials.
After this add below Scripts folder in your Solution:
MyScripts.rar (164.47 kb)
After this Open your _references.js file and Add following lines:
/// <reference path="../myscripts/init.js" />
/// <reference path="../myscripts/microsoftajax.js" />
/// <reference path="../myscripts/sp.core.js" />
/// <reference path="../myscripts/sp.js" />
/// <reference path="../myscripts/sp.runtime.js" />
/// <reference path="../myscripts/sp.ui.dialog.js" />
Make sure Options are set correctly:

So after all the configurations, your Solution will look like below image:

This looks fine.
See IntelliSense working fine:

Voila! Happy Coding