fixed a NullReferenceException on TilesetBuilder export

closes #4506
Added a camera to the A10. That spawns as they attack, and is destroyed as they leave
Added INotifyKilled to AttackBomber
Merge pull request #4721 from Smilex/A10_vision

closes #4696
closes #4687
Update CHANGELOG

#4721
Merge pull request #4714 from Mailaender/tile-export-nre

Fixed a NullReferenceException on TilesetBuilder export
move the temperat terrain extension into it's own folder
added old town urban terrain by @CombineCR

http://www.sleipnirstuff.com/forum/viewtopic.php?f=83&t=16117
water debris also belongs to the temperat terrain expansion
eddies cobble polish