Combinational cipher function

Cipher function without any clock. Works very fast.
Hope that delays won't be big after on-chip synthesis.

	new file:   src/f.vhd
DES structure
Structural DES implemented. Tests are bad (the output is equal to input with different keys)
Working DES encryption

Tested with the help of http://seit.unsw.adfa.edu.au/staff/sites/lpb/src/DEScalc/
Everything is working fine but synthesis takes long time. Maybe because of s1...s8 blocks with it's internal table.

	modified:   src/des.vhd
	modified:   src/des_it.vhd
	modified:   src/key_PC1.vhd
	modified:   src/key_PC2.vhd
	modified:   src/s1.vhd
	modified:   src/s2.vhd
	modified:   src/s3.vhd
	modified:   src/s4.vhd
	modified:   src/s5.vhd
	modified:   src/s6.vhd
	modified:   src/s7.vhd
	modified:   src/s8.vhd