LoadInstrument now has a new property called RewriteSpectraMap. If it is true (the default) then a new spectra map and axis are created on the input workspace and a 1:1 mapping of spectra->detector ID is set up. This should cure the issue that users of Python algorithms and CreateWorkspace don't get anything that is that useful. LoadEventNexus has also been updated to handle spectra rather than single pixel IDs for all files rather than just ISIS ones. A little tidy up is still required but the functionality is complete. Re #3106