MT_City.lua now compatible with whowards dll mod

-Made a new variable in Cat_misc.sql: CEP.MAXIMUM_BUY_PLOT_ADDITIONAL
that is used in MT_City.lua to increase the radius where it is
determined which plot has the best value for purchase
-The radius in MT_City.lua is now determined as
(GameDefines.MAXIMUM_BUY_PLOT_DISTANCE+Cep.MAXIMUM_BUY_PLOT_ADDITIONAL)