#1116 #1117 Add command usage hints and remove unused message keys

- Add usage message on argument mismatch where available
- Remove unused message keys
- Create tool task to search for a message key's usages and to find unused keys

src/test/java/fr/xephi/authme/command/executable/unregister/UnregisterCommandTest.java

@@ -4,6 +4,7 @@ import fr.xephi.authme.data.auth.PlayerCache;
 import fr.xephi.authme.message.MessageKey;
 import fr.xephi.authme.process.Management;
 import fr.xephi.authme.service.CommonService;
+import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -13,6 +14,8 @@ import org.mockito.junit.MockitoJUnitRunner;
 
 import java.util.Collections;
 
+import static org.hamcrest.Matchers.containsString;
+import static org.mockito.hamcrest.MockitoHamcrest.argThat;
 import static org.mockito.BDDMockito.given;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
@@ -71,4 +74,17 @@ public class UnregisterCommandTest {
         verify(management).performUnregister(player, password);
     }
 
+    @Test
+    public void shouldStopIfSenderIsNotPlayer() {
+        // given
+        CommandSender sender = mock(CommandSender.class);
+
+        // when
+        command.executeCommand(sender, Collections.singletonList("password"));
+
+        // then
+        verifyZeroInteractions(playerCache, management);
+        verify(sender).sendMessage(argThat(containsString("/authme unregister <player>")));
+    }
+
 }