Full mesh partial replication protocol.

[cmeiklejohn]

• Track interest groups, allow interest and disinterest.
• Filter updates based on interest groups.
• ObjectFilterFun everywhere must be a two arity call and take the metadata.
• Object metadata should allow specification of which groups it belongs in.
• Because of transitive delivery, adapt, because some nodes will rely on transitivity to ensure convergence, which means a simple 1-1 exchange will only work under full replication.
• Ensure functionality under partial replication.

[cmeiklejohn]

Will address transitive work in a subsequent commit.