Consistency for emf casing

[samreid]

During #103 we observed this code in PickupCoil.ts:

    this._biggestAbsEmf = 0.0;

    // Check that maxEMFProperty is calibrated properly.
    if ( FELQueryParameters.calibrateEMF ) {
      this._emfProperty.lazyLink( () => this.calibrateMaxEMF() );
    }

    this.maxEMFProperty = new NumberProperty( options.maxEMF, {

We saw that some variables have Emf and some have EMF. We recommend consistency here.

[pixelzoom]

The only variable I found was _biggestAbsEmf. I renamed it to largestAbsoluteEMF.

I like how you used "emf" in the issue title :)