Obscure detail in that if you teleport right on a chunk line, it
adds +1 to your collision check and will check the unloaded neighbor.
but the call to load the chunk then returned null if it was pending unload, such
as the load we did in Player List
However we want gen=true for players here anyways, so use getType
While there is more down the collision system, remove some of the wrapping
Spliterator stuff as even this wrapper stream has shown up in profiling.
With other collision optimizations, we might also even avoid inner streams too.
The collision code takes an AABB and generates a cuboid of checks rather
than a cylinder, so at high velocity this can generate a lot of chunk checks.
Treat an unloaded chunk as a collision for entities, and also for players if
the "prevent moving into unloaded chunks" setting is enabled.
If that setting is not enabled, collisions will be ignored for players, since
movement will load only the chunk the player enters anyways and avoids loading
massive amounts of surrounding chunks due to large AABB lookups.
Fixes#3321
