make Nexus file compatible with old libray
currently the file written can only be opened by HDF5 lib>1.10.*. An option should be added so that a Nexus file which is compatible with HDF5 1.8.* can be created.
Edited by Yuelong Yu
currently the file written can only be opened by HDF5 lib>1.10.*. An option should be added so that a Nexus file which is compatible with HDF5 1.8.* can be created.