3' overhang must be added to the direct strand instead of reverse-complement

Add a fragment to the new molecule content in the "Construct Molecule" dialog, select it and click the "Edit Overhangs" button. The "Edit Molecule Fragment" dialog appears. When a custom overhang is added to the "3' End" in the dialog, it is actually added to the 5' end of the reverse-complement strand.

A user should be able to select the strand to add the overhang to. By default, the direct strand should be used.

Assure also that overhangs are correctly treated when fragments are created (both using the digestion and from a sequence region).

Maybe it would be better to also add selection of the strand to the "Create DNA Fragment" dialog.