Continued work on the buy functionality. It is almost complete, it is now possible to choose unit to produce and buy new units.
There is a limit of max 4 units, after this the oldest unittype will be pushed out.
The server-side functions are now mostly done for this also. Including checks that the city is allowed to produce the selected kind of unit, and that the player can afford the new units he tries to buy. We cant trust the info from the client-side unfortunately, so everything needs to be doublechecked at serverside
Still need to make an extra verification at end turn/save game on client to see that all city-updates are synced to the serverside, and if not send them again.