added license/copyright in quickstart examples
update #279: more explicit options in Exporter
 - `exporter.geometry` is a string : change_coords_only, change or static 
 - `exporter.file-type` is a string : ascii, binary

the former allows to save a lot of disk space of used in static mode (only one
mesh saved) otherwise by default change_coords_only will tell the ensight
reader to load only the point coordinates for faster mesh load