Scaled output of export.py

Now each field has a min and a max, and it will linearly scale the value
within that range, so that 0 <= v <= 1.

i.e. if (min, max) == (-20, 100) and v == 40, then export.py will output
(40 - -20) / (100 - -20) = 60/120 = 0.5
Added JSON data to repo