Singapore and tutorial changes

Hello everyone! We've recently expanded the Mini Metro team and have been getting through the backlog much faster now. We've got a new map for you and some long-awaited changes to the tutorial. Plus a small quality-of-life fix that we could sneak in:

• Journey to the island city-state of Singapore and lay some tracks. • More explicit tutorial text to more fully explain some aspects of the game. • The direction of trains is shown when paused!

Happy commuting!