+ * - version : define the version of MED file format, coded with major and minor digits (release digit not used)
+ * for instance med 3.2.1 is coded 3*10+2 = 32, med 4.0.0 is coded 4*10+0 = 40.
+ * The rules of compatibility to write a mesh in an older version than the current version
+ * depend on the current version. For instance, with med 4.0 it is possible to write/append
+ * med files in 4.0.0 (default format) or 3.2.1 or 3.3.1 formats.
+ * The minor must be between 0 and the current minor version of MED file library.
+ * If version is equal to -1, the version is not changed (default).