This is how to reproduce the bug: have a layout with two
layers. Select two shapes of different layers and delete them.
One layer is not updated and only after zooming/panning the
shape will disappear on this layer.
* Modification of the mapping is possible now
(#map used to ignore mappings if there was one
already)
* Added DropCell mapping (also for RBA)
* Added unit tests for cell mapping, layer mapping
db::merge_layouts, db::copy_shapes and db::move_shapes