Rename class City to Player_city.  New class City is a base class from which Player_city and AI_city are derived.  It's as simple as it can be, and several functions have been moved there.
New code to handle new class Player_city (it has fire_citizens() while City does not).
Rename City to Player_city.  Call new function Player_city::start_new_city() which initializes population, resources, etc. after we've picked our race.
Rename City to Player_city.
Race_datum now has an int array called starting_resources, which tracks the resource cities of this race get to start with.  Note that ALL cities, regardless of race, start with the maximum possible amount of food (10 days' supply).