o Removed features:
    - The PortForwarding and PortForwardingHelper features have been
      removed. The reasoning is, given that implementations of NAT traversal
      protocols within common consumer grade routers are frequently buggy, and
      that the target audience for a NAT punching feature is a perhaps
      less-technically-inclined relay operator, when the helper fails to setup
      traversal the problems are usually deep, ugly, and very router specific,
      making them horrendously impossible for technical support to reliable
      assist with, and thus resulting in frustration all around.  Unfortunately,
      relay operators who would like to run relays behind NATs will need to
      become more familiar with the port forwarding configurations on their
      local router.  Closes 25409.