Search and replace: Delete instances crashes KLayout

[klayoutmatthias]

This refers to https://www.klayout.de/forum/discussion/2478

A test case is available.

[klayoutmatthias]

The problem is in the ambiguity between instances from cells from a cell tree (the instances inside the child cells) and the instance-expanded tree (also "instances of"). With "delete instances of TOP...*" the child cells are visited multiple times as "instances of ..." denotes the instance-expanded tree and at the second visit the error is thrown.