added the idea of each line of a column corresponding to a vector, with

the added informations of the number of elements per line and the
elements' names in the column's header structure

src/obitypes.h

@@ -73,6 +73,6 @@ size_t obi_sizeof(OBIType_t type);
  * @since May 2015
  * @author Eric Coissac (eric.coissac@metabarcoding.org)
  */
-size_t obi_array_sizeof(OBIType_t type, size_t nbelements);
+size_t obi_array_sizeof(OBIType_t type, size_t nbelements, size_t nb_elements_per_line);
 
 #endif /* OBITYPES_H_ */