A stereo encoder factory encoding double bond configurations by 2D and 3D
coordinates. This factory will attempt to encode all double bonds that meet
the following conditions. Are not -N=N- bonds, non-cumulated,
non-query and have each double bonded atom has at least one substituent. In
future the encoding rules may be more strict or even configurable but
currently they may be over zealous when encoding configurations with 3D
coordinates. This class is intended to be used with a the hash
encoding classes and is easier used via the HashGeneratorMaker.