Post Jam update

A small quick update after the Game Jam.

• Fixed high score display
• Fixed an issue where some tiles did not get bonus added.
• made it so that start and finish tiles themselves won't give any points even if affected by bonuses
• added portal tile
• Tile selection now provides description of tile effects

I'm also thinkging about improving graphics but now sure what direction should I go. Will focus on adding things suggested in coments first.