Merge ANN decoding information from input FSRs to the output FSR
When merging files, we get the same ANN decoding maps reported many times in the output FSR as part of the input FSRs.
The proposed change effectively merges the ANN decoding maps from the input FSRs into one map at the top level of the output FSR, removing the nested copies, to significantly reduce the size of the final FSR.
Closes #395
Edited by Chris Burr