Fix #279: Add spectate check to stop_follow

[Cooldude2606]

Fixes the issue of spawning a new character when spectate is stopped while follow is active. This was caused by the following logic path:

1. stop_spectate would return you to your orginal body.
2. on_tick for follow would see you had a character and attempt to stop itself with stop_follow
3. Because start_spectate was successful in start_follow it assumes that stop_spectate needs to be called.
4. However, because it has already been called once it now has no reference to your character, this triggers a respawn.
5. Respawning disconnects your orginal body and gives you a new one.