bot can hear sounds now. add some motion API.

bot/motion.go

@@ -1,12 +1,13 @@
 package bot
 
 import (
+	"fmt"
 	"github.com/Tnze/go-mc/data"
 	pk "github.com/Tnze/go-mc/net/packet"
 )
 
 //SwingArm swing player's arm.
-//hand could be 0: main hand, 1: off hand
+//hand could be one of 0: main hand, 1: off hand
 func (c *Client) SwingArm(hand int) error {
 	return c.conn.WritePacket(pk.Marshal(
 		data.AnimationServerbound,
@@ -22,9 +23,23 @@ func (c *Client) Respawn() error {
 	))
 }
 
+//UseItem use the item player handing.
+//hand could be one of 0: main hand, 1: off hand
 func (c *Client) UseItem(hand int) error {
 	return c.conn.WritePacket(pk.Marshal(
 		data.UseItem,
 		pk.VarInt(hand),
 	))
 }
+
+//Chat send chat as chat message or command at textbox.
+func (c *Client) Chat(msg string) error {
+	if len(msg) > 256 {
+		return fmt.Errorf("message too long")
+	}
+
+	return c.conn.WritePacket(pk.Marshal(
+		data.ChatMessageServerbound,
+		pk.String(msg),
+	))
+}