Implement sq key userid revoke --name and --email.

- User ID is an OpenPGP concept, whereas users think in names and
    email addresses.

  - See #30.

src/cli/key/userid.rs

@@ -198,6 +198,7 @@ instead of the current time.",
 )]
 #[clap(group(ArgGroup::new("cert_input").args(&["cert_file", "cert"]).required(true)))]
 #[clap(group(ArgGroup::new("revoker_input").args(&["revoker_file", "revoker"])))]
+#[clap(group(ArgGroup::new("cert-userid").args(&["name", "email", "userid"]).required(true)))]
 pub struct RevokeCommand {
     #[clap(
         long,
@@ -249,18 +250,39 @@ for the file to contain more than one certificate.",
     )]
     pub revoker_file: Option<FileOrStdin>,
 
+    #[clap(
+        long = "name",
+        value_name = "NAME",
+        help = "Revoke the given name user ID",
+        long_help = "\
+Revoke the given name user ID.  Must match a user ID exactly.  To revoke
+a user ID that contains more than just a name, use `--userid`.",
+    )]
+    pub name: Option<String>,
+
+    #[clap(
+        long = "email",
+        value_name = "ADDRESS",
+        help = "Revoke the given email address user ID",
+        long_help = "\
+Revoke the given email address user ID.  Must match a user ID exactly.
+To revoke a user ID that contains more than just an email address name,
+use `--userid`.",
+    )]
+    pub email: Option<String>,
+
     #[clap(
         long,
         value_name = "USERID",
-        help = "The user ID to revoke",
+        help = "Revoke the given user ID",
         long_help = "\
-The user ID to revoke.
+Revoke the given user ID.
 
 By default, this must exactly match a self-signed User ID.  Use \
 `--force` to generate a revocation certificate for a User ID that is \
 not self signed."
     )]
-    pub userid: String,
+    pub userid: Option<String>,
 
     #[clap(
         value_enum,

src/commands/key/userid.rs

@@ -35,7 +35,13 @@ use crate::cli::types::FileOrStdout;
 use crate::common::NULL_POLICY;
 use crate::common::RevocationOutput;
 use crate::common::get_secret_signer;
-use crate::common::userid::{lint_userids, lint_names, lint_emails};
+use crate::common::userid::{
+    lint_email,
+    lint_emails,
+    lint_name,
+    lint_names,
+    lint_userids,
+};
 use crate::parse_notations;
 
 /// Handle the revocation of a User ID
@@ -51,7 +57,7 @@ impl UserIDRevocation {
     /// Create a new UserIDRevocation
     pub fn new(
         sq: &Sq,
-        userid: String,
+        uid: UserID,
         force: bool,
         cert: Cert,
         revoker: Option<Cert>,
@@ -62,7 +68,7 @@ impl UserIDRevocation {
         let (revoker, mut signer)
             = get_secret_signer(sq, &cert, revoker.as_ref())?;
 
-        let uid = UserID::from(userid.as_str());
+        let userid = String::from_utf8_lossy(uid.value()).to_string();
 
         let revocation_packet = {
             // Create a revocation for a User ID.
@@ -516,6 +522,16 @@ pub fn userid_revoke(
         panic!("clap enforces --cert or --cert-file");
     };
 
+    let userid = if let Some(n) = command.name {
+        lint_name(&n)?;
+        UserID::from(n)
+    } else if let Some(e) = command.email {
+        lint_email(&e)?;
+        UserID::from_address(None, None, e)?
+    } else {
+        UserID::from(command.userid.expect("one of the three must be given"))
+    };
+
     let revoker = if let Some(file) = command.revoker_file {
         let br = file.open()?;
         Some(Cert::from_buffered_reader(br)?)
@@ -529,7 +545,7 @@ pub fn userid_revoke(
 
     let revocation = UserIDRevocation::new(
         &sq,
-        command.userid,
+        userid,
         sq.force,
         cert,
         revoker,