Support for clear signatures
I think that sequoia doesn't support clear signatures, but I'm not sure. If we don't, we should.
$ echo foo | gpg -u AACB3243630052D9 --clear-sign
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512
foo
-----BEGIN PGP SIGNATURE-----
iQEzBAEBCgAdFiEEwD+mQRsDrhJXZGEYciO1ZnjgJSgFAlwnlOsACgkQciO1Znjg
JSilTAf/SKlpeMqSECgmqvOcFcDhH2giKQ65htOPjO1UONS6pOcJvGgcH+QdHFna
+C53v8DtYznT96i8w7C/1KRQe72nq0KKRlRTdEcae2b1ypK+XRxxAO94aqqiL3Cf
4XP1rX3LoYruMCAnn10pUtxptus/XWERYHHJdNkG4RCye3qGya4HciDyUtZs4REb
nBbi+H8dnePC1PVjwBIltdCc21NuAG5J1WV8a3DMRtlSz11XHhlTtZjnC2HFDldO
l+PzVeSU0GNJArjaGLjhP016onDt1C1UhA89OaDUHzqHJYES7Xdmsw6cpPZn2CVR
9kY9/zjW4vWfxodD+Oenpqx3cjwoGg==
=8ecE
-----END PGP SIGNATURE-----