[Gmecm] $58 simplification

[Rob Handley]

I've spent the whole weekend trying to define a calibration that cuts down 
on the number of adjustments that code $58 makes in preparation for setting 
up base VE tables _from_scratch_.

I've been adopting a 'belt and braces' approach where I set one or more 
thresholds to turn off a factor (e.g. EGR/DFCO) and all the values that the 
factor would apply if it was on - so that they would have no effect.

There's a couple that I'm not clear on:

- how to set the F28 and F75 arrays to make EGR have no effect
- how to set KDFCOG to make DFCO have no effect

Can anybody help?

Robin