Add des from nettle library.

	* Makefile.am: Add nettle-des
	* Makefile.in: Regenerate
	* analysis/simulator.in: Add nettle-des
	* configure: Regenerate
	* configure.ac: Add nettle-des
	* src/nettle-des/Makefile.am: Create
	* src/nettle-des/Makefile.in: Regenerate
	* src/nettle-des/des.c: Import des from the nettle library
	* src/nettle-des/desCode.h: Ditto
	* src/nettle-des/descore.README: Ditto
	* src/nettle-des/keymap.h: Ditto
	* src/nettle-des/rotors.h: Ditto