nblast evaluation

[bogovicj]

• Compute pairwise nblast scores (in progress: https://github.com/saalfeldlab/template-building/blob/master/R/analyze_pairwise_nblast.R )
• be able to transform swcs
• need inverse of displacement field for the above ( see https://github.com/bogovicj/imglib2-realtransform/blob/cf0139c3fe1ba12e76f8d9b9c2f112e6e679b23a/src/main/java/net/imglib2/realtransform/InvertibleDeformationFieldTransform.java)

Fixed

Issue: The swc files generated by
https://github.com/saalfeldlab/template-building/blob/master/scripts/antsEvalNblast
contain all 0's