Complete message command parser and listener

The message command listener is now completed and the bot now also supports message-based commands with multiple aliases.

src/main/java/wtf/beatrice/hidekobot/commands/message/CommandsCommand.java

@@ -0,0 +1,43 @@
+package wtf.beatrice.hidekobot.commands.message;
+
+import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
+import wtf.beatrice.hidekobot.Cache;
+import wtf.beatrice.hidekobot.objects.MessageCommand;
+
+import java.util.Collections;
+import java.util.LinkedList;
+
+public class CommandsCommand implements MessageCommand
+{
+
+    @Override
+    public LinkedList<String> getCommandLabels() {
+        return new LinkedList<>(Collections.singletonList("commands"));
+    }
+
+    @Override
+    public boolean passRawArgs() {
+        return false;
+    }
+
+    @Override
+    public void runCommand(MessageReceivedEvent event, String label, String[] args) {
+
+        StringBuilder commandsList = new StringBuilder();
+        commandsList.append("Recognized message commands: ");
+
+        LinkedList<MessageCommand> messageCommands = Cache.getMessageCommandListener().getRegisteredCommands();
+        for(int i = 0; i < messageCommands.size(); i++)
+        {
+            commandsList.append("`")
+                    .append(messageCommands.get(i).getCommandLabels().get(0))
+                    .append("`");
+            if(i+1 != messageCommands.size())
+            { commandsList.append(", "); }
+
+        }
+
+        event.getMessage().reply(commandsList.toString()).queue();
+
+    }
+}

src/main/java/wtf/beatrice/hidekobot/commands/message/HelloCommand.java

@@ -0,0 +1,29 @@
+package wtf.beatrice.hidekobot.commands.message;
+
+import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
+import wtf.beatrice.hidekobot.objects.MessageCommand;
+
+import java.util.Arrays;
+import java.util.LinkedList;
+
+public class HelloCommand implements MessageCommand
+{
+
+    @Override
+    public LinkedList<String> getCommandLabels() {
+        return new LinkedList<>(Arrays.asList("hi", "hello", "heya"));
+    }
+
+    @Override
+    public boolean passRawArgs() {
+        return false;
+    }
+
+    @Override
+    public void runCommand(MessageReceivedEvent event, String label, String[] args)
+    {
+        String senderId = event.getMessage().getAuthor().getId();
+        event.getMessage().reply("Hi, <@" + senderId + ">! :sparkles:").queue();
+    }
+
+}