Hover over image under point / rect as well

[nikolausWest]

When hovering over an image with points or rectangles on it, the image hover preview suddenly disappears when we hover over a point or rectangle. This is particularly annoying because the position of the point or rectangle boundary is usually the most interesting place to inspect the image.

[Wumpf]

An easy way to go about this is to never stop the picking ray at opaque non-image objects in 2D views as we do now + give images priority in the list of hovered things.

Once we're in a 3D view, the solution is less obvious - a picking ray should still stop in front of opaque unrelated objects ofc.. Meaning that we'd need to know for every object how it is grouped together

But it's probably okay to have slightly different picking behavior in those views given that image picking in 3d isn't a super important workflow.

[emilk]

Will fix after

• GPU picking for hover/select #1615