* Renamed tile.hasUnique, deprecated `Indestructable`, unique for citadels
Also refactored the consumption of (great) people out of UnitActions.
* Reworked when improvements can be build somewhere for more clarity
* Made resources improvable by multiple improvements; Offshore Platform
* Fix compatability
* WIP
* Fixed the tests, but better
* I suppose I might as well update this now that we're a version later
* Add a very simple display for the religion in a city
* Added missing credits for shrine
* Added Great Prophet unit
* Great prophets can now be generated using faith
* Great Prophets can now construct holy sites
* Great Prophets can now spread their religion to friendly cities
* Holy site can only be constructed if the great prophet hasn't spread religion yet
* Added missing translation string
* Fixed more translation problems
* Implemented requested changes
* Added the nation of the Netherlands
* Added Sea Beggar, Dutch unique unit
* Added polder improvement, Dutch unique improvement
* Added national ability