Write a model for nested graphs
Extend the Blueprints graph by a NestedGraph functionality.
There is already PartitionGraph in Blueprints, which is not very handy to use, because you have to know about the partitions names. But this could be used as a basis. https://github.com/tinkerpop/blueprints/wiki/Partition-Implementation
Use the WrappedGraph class or the WrapperGraph interface. https://github.com/tinkerpop/blueprints/blob/master/blueprints-core/src/main/java/com/tinkerpop/blueprints/util/wrappers/wrapped/WrappedGraph.java https://github.com/tinkerpop/blueprints/blob/master/blueprints-core/src/main/java/com/tinkerpop/blueprints/util/wrappers/WrapperGraph.java
Required by #19