Required decency which is inherited from builder3d.

Change-Id: I025e14891170b9249f34a4bbf6d5323dfd4aa5d5
Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>
Aromatic selenium can be parsed from SMILES. The current aromaticity perception doesn't consider Se but thats not related to SMILES parsing.

Change-Id: I88f6848775912e88f1a7f1d60634dca88970039e
Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>