ADDED memberOf() function for DRC rule expressions.
Also fixes a bug in several of the pickers where the event wasn't
being correctly passed.
Fixes https://gitlab.com/kicad/code/kicad/issues/5647
ViewGetLOD() returns the minimal value of a zoom to show an item.
However a zoom is a double, and using int as minimal value does not
allows setting a correct value in some cases.
ADDED: Allow DXF/SVG graphics to be imported as a group
Also, cleanup the placement routine to allow the edit tool's flip
and rotate routines to be used when placing the items.