[CIV5] Balance request - hard-fixed first ring city plots

[OneFuriousDon]

As mentioned in the title I would like to suggest making - if feasible - first ring city plots unstealable/unbuyable so that they never change their ownership.
It would balance America's special feature and AI tendency to steal land with citadels.

Bonus idea: It could be worth considering if City States shouldn't always raze captured cities either starting the process immediately or (if possible) delayed for a couple of turns.