NetDB:

  - Move net.i2p.kademlia package from i2psnark to core, and convert
    netdb to use it.
  - Delete old implementation in netdb
  - Fixups in netdb for generics
  - Add debug output to /debug

  This is the next step in the development plan, in which we previously:
    - Copied the code from netdb to the i2p.zzz.kademlia branch, fixed it,
      and made it generic for hash size (June 2012);
    - Moved it from the i2p.zzz.kademlia branch to the i2p.i2p.zzz.dhtsnark
      branch, and implemented KRPC with it (June 2012);
    - Propped it from i2p.i2p.zzz.dhtsnark to trunk for 0.9.2 (July-Sept. 2012);
    - Proved it out in 0.9.2 - 0.9.9 (Oct. 2012 - Nov. 2013)

  The plan was to maintain the KBucketSet public methods throughout the development
  so we could drop the new version back into netdb, so here we drop it in.

  Setting of K=16, B=3 is just an initial guess, to be reviewed.
  This moves about 18 KB from i2psnark.jar to i2p.jar and removes about 12 KB from router.jar.
  Unit test fixup: todo.