encrypt-dsa.test, encrypt.test, genkey1024.test, plain-1.asc,
plain-1-pgp.asc, plain-2.asc, plain-3.asc, pubring.asc, secring.asc,
sigs.test: Rework tests to work properly with a gpg binary that doesn't
have all ciphers and all pk algos. Basically, we test for the ciphers we
have, only test signing with non-160-bit hashes with RSA (we test all
hashes as hashes). Test all key lengths of AES.
