Linked Unit Types and Promotions in Civilopedia

Added new unique - "Automatically built in all cities where it is buildable"

By SeventhM:
- Added unique "May travel on Water tiles without embarking"
- Change the default cost of buildings and the default time of tile improvements

By xlenstra:
- Spies now occasionally steal technologies
- Spies in cities that are captured or destroyed now go to the hideout

Better mod conflict prevention - By SomeTroglodyte