let players walk if their position changes and not if they hold specific keys

let players walk if their position changes and not if they hold specific keys
and disable the animation update globalstep on singleplayer mode because it's not necessary and 3d person view is independent from this globalstep
The code under here isn't indented properly.  You shouldn't indent it though, it would be better to do:
```Lua
-- Skip animations in single-player because they're not needed.
if minetest.is_singleplayer() then
	return
end
```
(Yes, you can return from files, Lua loads them like regular functions)

Another option is to seperate the global-step function from the `register_globalstep()` call and put the `register_globalstep()` call in the if statement.  This has the advantage of not having unexpected results when you add code to the bottom.
```Lua
local funtion update_animations(dtime)
	...
end
-- Skip animations in single-player because they're not needed.
if not minetest.is_singleplayer() then
	minetest.register_globalstep(update_animations)
end
```