reduce about 20 numbers of the common infected in all campaign.

thanks to Jo,now it should work when you use solo game in menu to start a game.Here is his solution https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3026853730

after i tested,i think spwn interval is a little bit long,so i reduced mob spwn interval and hope it't can make game more tension.
interval of game difficulty:
easy:240-180(you will have more time to run,it's Original settings)
rest:140-120(zombie will attack you about every 2 minutes)

note:you must use consle command map to start game,otherwise this mod will not apply,i don't know why but the original mod can used in solo game mode and don't have to use command to start the game.If you know how to avoid this problem,please tell me,thank you