7/8/96:
	Added next_block and reset methods to Crypt::CFB
	Modified encrypt method so that encrypt("xy") is
	now the same as encrypt("x") and encrypt("y")
	concatenated together.
	This may break some existing code, but is hopefully
	for the better.  As a workaround, call next_block
	before your encrypts.

5/12/96:
	Added SHA0 and HashSHA0, since Crypt::SHA now uses
	the fixed SHA (ie SHA-1).
