Sandbox: Add an option to change province owner and add/remove cores

[Iceman 295]

I was rewatching the Sandbox mode video and got a simple idea that would improve it a bit.

In the Provinces tab, add an "Owner" option to allow the player to change the owner of a province. This would be useful, for example, to correct undesirable borders after AI peace treaties.

In the same Provinces tab, add an "Add core" and "Remove core" to add/remove cores. This would be useful to add new cores mid-game or remove cores of extinct civilizations.

[Łukasz Jakowski 13,387]

Sandbox: Change province owner in mid-game

 

 

[Wayne23lololh 1,645]

Nice