Flying state is not saved when reloading world

If you leave a world when flying in creative mode and rejoin, you will no longer be flying.

Steps to reproduce:

1. Join a world

2. Set your gamemode to creative

3. Begin flying

4. Exit the world whilst still flying

5. Rejoin the world

Observed Results:

• You are no longer flying

Expected Results:

• You should still be flying as this is how you logged off