Pause the game when you go back to the menu

[xiaoheh]

There is a menu button on the upper right of the window that allows going back to the menu from the game, and resuming the game from the menu later by clicking "start/resume". However the timer of the game doesn't pause in this process.

Estimate: 150 pts

[xiaoheh]

100 more points for separating "start/resume" to two buttons: "resume" that resumes the game, and "start" that starts a new game

[asyung]

F16 OK (100 pts)

[hyeminyoo]

Currently, the code is really complicated and this issue is hard to fix. We tried fixing this but ended up not finishing it. Refactoring the code is suggested before tackling this issue.

[seemantasaha]

W18 OK. Need to check running the application. Points may vary from 100-300 points.