Moving assignment iterator to my BN project, since it is always used with BNs, and this way, the BN project can stay self-contained.
Created a value-dag interface to reduce replication up the interface hierarchy
Inserted the value-dag interface into the interface hierarchy
Added score package (for BD scores). Depends on Apache Commons 3.2 (for Gamma function)
Inserted value dag into BN's interface hierarchy
Added abstract implementation for parentAssignments