Add function to revoke a user identity.

Done with Context::revUid, not with UserID::revoke.

Does not remove the identity.

N.B. : if the uid is revoked a second time, Error::code is 0.

GpgMEWorker.h

@@ -100,6 +100,19 @@ public:
     const Error AddUserID(const char * keyFpr, const string& passphrase,
                           const string& name, const string& email,
                           const string& comment);
+    /**
+     * Revoke a user identity. Does not remove the identity.
+     * \n N.B. : if the uid is revoked a second time, Error::code is 0.
+     * @param keyFpr
+     * @param passphrase
+     * @param name
+     * @param email
+     * @param comment
+     * @return 
+     */
+    const Error RevokeUserID(const char * keyFpr, const string& passphrase,
+                          const string& name, const string& email,
+                          const string& comment);
     /**
      * Creates a pair of secret and public keys with the default engine
      * algorithms. Default expiry time is 2 * 365 days.