1.7.10: Fix player position too high on login. Closes #87

Adds a new TeleportPlayer_NoGround packet, which is subtly different
from TeleportPlayer_NoConfirm. The flags u8 is replaced with an
on_ground bool, but more importantly the Y position is the eyes
position, so we have to translate to feet position for the client.

1.7.10: https://wiki.vg/index.php?title=Protocol&oldid=6003#Player_Position_And_Look
1.8.9: https://wiki.vg/index.php?title=Protocol&oldid=7368#Player_Position_And_Look

Author: iceiix

protocol/src/packet.rs

@@ -1310,6 +1310,14 @@ state_packets!(
                 field pitch: f32 =,
                 field flags: u8 =,
             }
+            packet TeleportPlayer_OnGround {
+                field x: f64 =,
+                field eyes_y: f64 =,
+                field z: f64 =,
+                field yaw: f32 =,
+                field pitch: f32 =,
+                field on_ground: bool =,
+            }
             /// EntityUsedBed is sent by the server when a player goes to bed.
             packet EntityUsedBed {
                 field entity_id: VarInt =,

protocol/src/versions/v1_7_10.rs

@@ -42,7 +42,7 @@ protocol_packet_ids!(
             0x05 => SpawnPosition_i32
             0x06 => UpdateHealth_u16
             0x07 => Respawn
-            0x08 => TeleportPlayer_NoConfirm
+            0x08 => TeleportPlayer_OnGround
             0x09 => SetCurrentHotbarSlot
             0x0a => EntityUsedBed_i32
             0x0b => Animation