combined PGPPublicKey and PGPPrivateKey into a single subclass of PGPBlock
made extract_pgp_ascii_block into an instance member; refactored PGPBlock.parse slightly so it can begin working with non-ASCII armored data
added basic magic regex to reg.Magic
refactored slightly to use PGPKey instead of PGPPublicKey and PGPPrivateKey
began setting up test harness for PGPKeyCollection