Crash in Python binding

[klayoutmatthias]

Please refer to https://www.klayout.de/forum/comments.php?DiscussionID=989&page=1#Item_10 for the discussion.

The issue happens with this code:

poly = pya.Polygon(pya.Box(1, 2, 3, 4)).move(10, 20)
print poly

This code makes the application crash. Reason: "Polygon#move" returns a C++ reference which becomes invalid when the previously created polygon gets discarded. The solution is to use "moved" which returns a copy.

Apparently 0.24 could handle this case, hence this ticket.