some netdb changes

      - Add a per-cache stat
      - Limit each cache based on max memory
      - Disable in UDP MessageReceiver
      - Add clearAll() method to be called when under
        severe memory pressure; call from Router

      an IOE so we recognize it when it's throuwn

      - Concurrent
      - Workaround for Apache Harmony 5.0M13 Deflater bug

      into memory for every lookup

      - Remove some locks with concurrent

      will be transparently unpacked with unpack200. Savings is about 60%.
      Someday we will do this for suds, but we can do it for xpi2ps now.
    * build: Add updater200 target

      - More finals

      - getFramedAveragePeerClockSkew() now returns a long (ms);
        was a Long (s)
      - Implement NTP-style clock slewing so the clock is adjusted
        gradually
      - Implement clock strata so we prefer better clocks
      - Implement a timestamper in the transport so we will periodically
        update the clock even if NTP is not working
        This allows the router to converge the clock instead of simply
        hoping the first connected peer is correct.
      - Slow down NTP attempts after several consecutive failures

      - Check plugin key against all installed plugins
      - Reword some error messages
    * VersionComparator: add '-' and '_' as valid separators
      to better support plugin and java version checking

      - Allow method to check if we know about a key
      - Add method to extract without verifying

      - Cleanup and javadoc