[Dune] dune-curvilineargeometry & dune-curvilineargrid license now along dune license

[Benedikt Oswald]

Dear Dunies, the license of dune-curvilineargeometry and
dune-curvilineargrid has

been streamlined with the DUNE license, i.e. they are now the same as
for DUNE itself.

Greetings, Benedikt