add nMFI to final output

[Fersoil]

Output file should have an option to include the nMFI - normalized MFI.

As discussed, there are situations where samples have higher MFI than the standard curve. In this situation it does not make sense to convert to RAU, but we would still like to account for plate-to-plate variation. We can define nMFI = (MFI of sample)/(MFI of standard pool at the same dilution). For example, if samples on the plate are run at a dilution 1/400, then we should divide by the MFI of the standard curve at 1/400 dilution. You will need to specify a user-defined option because sometimes we run samples at different dilutions.