Currently have trail of different language to talk about samples-- physical specimen, specimen, material specimen, physical sample, material sample... Make consistent in vocabs and metadata with 'material sample'. This is consistent with Darwin Core TDWG wg decision (https://dwc.tdwg.org/list/#dwc_MaterialSample) and current OGC O&M/ISO19156 (http://www.opengis.net/doc/as/om/3.0).