Fix Envelope clone (closes #107)
Fix Envelope clone (closes #107)

Septima/jsts,kolosov-sergey/jsts,mikeatlas/jsts,mikeatlas/jsts,weftio/jsts,nachoalthabe/cluster_poligonal,mikeatlas/jsts,Septima/jsts,Geode/jsts,yeyan/jsts,circuits-io/jsts,circuits-io/jsts,kolosov-sergey/jsts,weftio/jsts,kolosov-sergey/jsts,weftio/jsts,Geode/jsts,Septima/jsts,Geode/jsts,yeyan/jsts