0.1.2   Fixed bug in pcp_derivekey() which derives encryption
	keys. it generated collisions due coding error, e.g.
	passphase 'a' resulted in the same encryptionkey as
	passphase 'r'. Now uses SHA256 witout the xor stuff,
	which was the cause for the bug. This also fixes a
	segmentation fault which occured invariably by entering
	an invalid passphrase.

	Added support for derived public keys using the -R
	option, which allows two peers to encrypt messages
	without the need to reveal their primary public keys.
	That way each peer will have another public key of
	the same source.

	Added more unit tests to reflect the above changes.

0.1.1   Changed output format of encrypted keys. now we
        encode it properly with the Z85 encoding and add
        a header and footer to it:

         -----BEGN CURVE25519 SECRET KEY-----
         0q<1MspXp=x>mBZsUJF:2#)o*!.nTKR8SK}0IfuMBmC1a&*?)JD4%$%I5<J2jj%m/k&$?lck
         EIKTfhPnSR8Vvcu9i7Znf/v+ZvU<}K#v@+t#5]i{9FGgJT$Lu*i+<-we&P9+)6LjN=NW(PLYt
         EU]wBzf{UrCgBNSHcGBT
         -----END CURVE25519 SECRET KEY-----

0.0.1   Initial version