implement nexus data format reader
@pellegrini I am adding this as an issue so we can track progress and have discussion. Do you have a reference for the file format? Are you planning to read instrument/detector geometry directly from the nexus file, or will be we continue to use the instrument XML resource files? If we are going to make nexus the primary data format for the tool moving forward into the future, I would like to write some scripts and/or small programs to convert Biodiff data to nexus format directly.