prod.in default inputs for CO2 coefficients are confusing

[dschlaep]

The default inputs for CO2 coefficients are confusing because there are four numbers (as if each number applies to one of the four plant functional types -- as used for the inputs earlier in the file).

# CO2 Coefficients: Coeff1 * ppm^Coeff2
# Biomass
# Coeff1 Coeff2
  0.127 0.3501 0. 0.
# WUE
# Coeff1 Coeff2
  22.464 -0.531 0. 0.

==> What are the zeros?

[Zachary-Kramer]

If I remember correctly, the issue was that VegProd.c expects 4 values for every line. The CO2 code only reads in 2, but 4 are required (which I forget why they are). I will revisit this code to see if this reasoning still holds or if there's a better way around it.

[dschlaep]

See comment #57: the four values per line are for the four plant functional types.

[Zachary-Kramer]

I'm implementing it like such:

Since issue #57 is a functional issue, and this one is a question, I'm going to combine them into just 57