- Change large MTU from 1492 to 1484 and small from 608 to 620
      for encryption padding efficiency
    - Enforce sent MTU limit
    - Increase receive buffer size from 1536 to 1572 so that excessive-sized
      packets sent by 0.8.9-0.8.11 routers aren't dropped
    - Limit the max acks in a data packet
    - Limit the duplicate acks in successive data packets
    - Only include acks that will fit in the mtu in a data packet
    - Correctly remove acks from the pending set after they are sent,
      so they aren't sent repeatedly
    - Don't pad data packets unless necessary
    - Debug logging and javadocs