Main menu + a few changes to appearance

To link the "PLAY GAME" option on the main menu to "scene1" you may need
to go into File>Build Settings and then drag the "main menu" scene and
"scene1" into the box.

Changes to appearance:
- I've made the background white.
- Centred the board in the screen.
- The game board is now lit by a spot light instead of a point light.
- I've added some graphics of some lego men, we don't have to keep them
but i thought we could use them somewhere. There's 3 in total, but 2 are
invisible right now.
- There also lit by a spot light.

I still haven't figured out why the lego bricks are making it spaz out
so I've left that bit out.