Version 3.21 - Tokyo map fixes

This patch fixes several problems in the Tokyo map, especially in the area around the Tokyo Skytree landmark.

• Improve the shape of the waterway immediately to the NorthWest of the Skytree.
  
• Move the Skytree a little ways eastward.
  
• Improve the construction of bridges above the Skytree (they sometimes started on land)
  
• Fix several visual holes in the Tokyo map.
  
• Repair two islands in the Northwest of Tokyo Bay, and one island in the Northeast of Tokyo Bay so that the construction grid appears overtop of the island.