Two bioentity were equals if they had the same id. Now, the two objects must be equal.
Constructors of BioEnzymeParticipant and BioReactant are now "protected". This avoids to create redundant participants. A BioCollection for each one has been created in the BioNetwork
The constant parameter is not saved anymore when loading a SBML file. It's not used in Met4j applications. If we want to save reactant attributes, we have to do at the reaction level now.
