Fix arrow type marker snapping to the ground

[FileEX]

Fixed #536 and #4000

[MegadreamsBE]

This is huge! I recently had to work with them (for enexes - for a certain project of mine) and it was a huge headache.

[TheNormalnij]

Does it affect other marker types?

[FileEX]

Does it affect other marker types?

This shouldn't affect anything else because other markers don't have such bug

[Lpsd]

As we're affecting markers here, all other marker types need to be tested. It's not enough to simply assume it won't cause other issues relating to the affected area.

I also just want to make a general point (not specifically related to this PR) that this kind of testing is also not what nightly should be intended for (it seems nightly often gets used as a testing bed due to lack of testing or review in the PR stage).

PRs should be clear on which areas they are affecting, what has already been tested (e.g; have you tested for regression in related areas?), and how it can be tested; it may be time to improve our pull-request template & overall flow.

If a PR has had sufficient testing/review and issues arise in nightly that's fine - but using it as an off-the-bat testing bed, explicitly due to a lack of testing or review at the PR stage, is not very ideal.

[FileEX]

Based on simple tests that involved creating markers and observing them, I didn't find any issues, as seen in the screenshot—markers like the 'cylinder' type behave correctly. The PR doesn't change anything except removing the Z-axis offset, which was originally intended for 'bouncing' markers for interiors (enex) in singleplayer.