* 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
