EGO Correction

I haven't used EGO Correction until now because, theoretically, it's not needed.  If all of the tables are set correctly Megasquirt can run the motor in open-loop and always inject the perfect amount of fuel to achieve the AFR target.

I've gotten close, but now I'm getting lazy and enabling EGO Correction is easier than trying to get all of the tables and corrections perfect.  It works particularly well in cruise conditions and keeps the AFR on the lean side at low loads to help save gas.  I'm not using it at idle because I find it induces oscillations and it's better to just to tune the idle VE table.