Do not include construction images in extrude/lathe/revolve/helix

To avoid unnecessary/annoying copies of images added in 2d sketches if they
are marked "construction" they will not be copied when creating solids.

Fixes: #1418

src/group.cpp

@@ -1180,6 +1180,11 @@ void Group::CopyEntity(IdList<Entity,hEntity> *el,
             break;
 
         default: {
+            if((Entity::Type::IMAGE == ep->type) && (true == ep->construction)) {
+                // Do not copy image entities if they are construction.
+                return;
+            }
+
             int i, points;
             bool hasNormal, hasDistance;
             EntReqTable::GetEntityInfo(ep->type, ep->extraPoints,