Fixed LIS checks in fast moving vehicles behaving unexpectedly

[derbismarck]

Closes #194

[diwako]

Just tested it. The flickering in fast moving vehicles is still happening. However it is less as it looks like the detection is more accurate to the visual simulation.

Still there is one change request, detailed above.

[derbismarck]

Acknowledged -- I was also seeing that flickering but thought it was specific to another change we'd made, it might have to do with the distance check being performed, I'll take a look in the near future and make the requested change.

[derbismarck]

Confirmed that in diwako_dui_nametags_fnc_calculateFadeValue, the value of _distance is not at fault, presumably because despite the distance command not being in visual time scope, the actual offset in position for both the player and the vehicle being checked against is identical. Observe output of the following to see that the error between an exact visual distance check and a object1 distance object2 check is less than a centimeter, assuming that both object1 and object2 are in the same vehicle, or if one is the parent vehicle of the other.

onEachFrame {systemchat str abs (vectorMagnitude ((getPosASLVisual object1) vectorDiff (getPosASLVisual object2)) - (object1 distance object2))};

For the case of a player looking at a crewmember of their vehicle, object1 would usually be player and object2 would be vehicle player, at least as it's currently written (more on that down below).

So that wasn't the issue. However, the issue is in diwako_dui_nametags_fnc_calculateFadeValue -- it's with the visibility check. I've committed a fix for that that now utilizes visual commands to get eyepos, similarly to the change made in the LIS code. That fixes the flickering for me. I also made a small performance change by removing the definition of _pos and instead putting it directly in the checkVisibility call. Here's it fixed: https://giant.gfycat.com/BleakActualKagu.mp4

All of that being said, there are still some issues with how diwako_dui_nametags_fnc_calculateFadeValue works, which I've already looked at fixing. I'll likely create a separate PR/issue for those. They're mostly to do with the fact that _distance is being taken as the distance between _player and vehicle _target even when _player and _target are both crew in the same vehicle, leading to unexpectedly high fade values if both the _player and the _target are in a large vehicle, far from the center of the vehicle, but very close to one another.

[diwako]

Finally gotten around and tested this. It does work as detailed in the post above. Also did some smallish performance testing and it was negligible as well