Lightened map cell backgrounds. Added modal for showing objectives. This...

AT

1) View mini-map and verify that cells (both visited and not visited) are lighter.

Verify that the objectives modal displays through the following means of access:

a) By clicking on the objectives div in the top right. Ensure close button works.

b) By clicking on the view objectives link in the pause menu. Ensure the 'Go back' button returns you to the pause menu.

c) Reaching an end-game screen by any method and clicking on the view objectives link. Ensure the 'Go back' button returns you to the game over screen.