z-index usage is subpar leading to clipping issues

[wojtossfm]

While the effect on a single character is correct when multiple character cross this seems to break.

A solution seems to be:

• to not actually set the z-index
• instead use it as a guide when ordering the children for each parent

Seemed in the scenes where I tried it this led to the expected ordering visually being maintained while removing the issue of multiple characters crossing and sprites clipping over each other in awkward ways.

[wojtossfm]

Not sure this is easily solvable and is in part an animation/character issue rather than an issue with the importer itself. The solution I mentioned in the initial comment would work for simple cases but there are ones where z-index appears to be used to change order between different layers of the hierarchy where simple ordering of children in godot wouldn't be enough. I'll leave this open as an enhancement could still be done to limit usage of z-index in the simpler cases and make it an importer option.

[wojtossfm]

A potential solution is also using a y-sort node (in case someone comes looking for an easy solve)