Object reference arrows too prominent

[eishiya]

When dealing with multiple Object Layers that have object references and displaying the object reference arrows, the display can easily get confusing, especially since the arrows are all drawn above everything else and aren't obscured by intervening layers at all. Short of hiding the other layers, there is no way to view or highlight the connections on just the current layers.

A few changes would help:

1. Draw the object references along with their relevant layers, rather than drawing them all at the end. This will allow the arrows to be obscured along with their objects. For references across layers, I think the arrow's tail should be drawn with the referencing object's layer, and the head should be drawn with the referenced object's layer. Illustration of how the arrows always being drawn at the top makes parsing them rather confusing:
2. When hovering or selecting an object, draw its arrows (outgoing and incoming) on top of everything, similar to how it's currently done for selected and hovered objects. This way, references can be clear when needed even if other layers are in the way.
3. (This should be a consequence of the first suggestion, but I'm mentioning it explicitly just in case.) When Highlight Current Layer is enabled, irrelevant arrows should be faded out just like the irrelevant objects are. This would mean the arrow heads would be highlighted when the current layer includes the references object, and the tails would be highlighted when the current layer includes the referencing object. Currently, they're just drawn on top of everything, making Highlight Current Layer not useful for navigating jungles of references:

An alternative solution suggested by @UliAbo on Discord is an option to only show arrows that touch the current layer. This would also work, but I think my more complex solution above would feel nicer to use, and it wouldn't require an extra setting.