Links between levels n and n+2

Apogée allows for the structure like this one:

Here we have a link between levels 1 and 3. The current code was not designed to treat this situation. I have created this structure in the test mode of Apogée, end generated an XML dump, attached here:

test_skip_stage.xml

This data results in an invalid DrawIO file:

So far we have not seen such structures in the real life, but they may occur.