DNA interface removed, java.lang.Object used instead. Only the class constructing the cell and the nucleus implementation are interested in the DNA. Therefore there is no need to define interface for it. It is the nucleus responsibility to know the expected type of the dna and cast it
ChainAwareChemicalHandler moved, interface Organic removed as not needed
minor fix
visibility reduced from public to package for helper class
the JSON-based DNA implementation renamed to DNA.
a bit of comments added
first working integration test