add background scale
allow max normalization value to be 1e10

 * looks like the NCD Data Reduction pipeline used 1e10 to get the
   values back into a more normal range instead of 1e-11
use sample thickness in normalization calculations

 * also fix using wrong set error method - use setError because
   we are using standard deviations
use rank of ONE instead of SAME

 * otherwise, background subtraction does not appear in list of possible
   steps
Merge branch 'SCI-2041'