0.5 Game re-balance and stuff

After watching some playtests I've made some changes (hopefully for the best) and fixed that should make the game easier to play:

• Generally slowed down and rebalanced all levels
• No more click and drag for changing directions, just click.
  • Upgraded intersections also work like this, if you click and hold one the color wheel will show up. 
• Instead of having the trains start after a  timer, there's now a "Go!" button.
• Doubled train delay window.
• Reduced size of clocks.
• Added option for full screen.
• Fixed weird track behaviour when building near stations.
• Fixed level transition for different aspect ratios.
• Fixed trains not dying and  getting stuck in limbo when exiting a station with wrong tracks in front.