o Major bugfixes:
    - Instead of writing destroy cells directly to outgoing connection
      buffers, queue them and intersperse them with other outgoing cells.
      This can prevent a set of resource starvation conditions where too
      many pending destroy cells prevent data cells from actually getting
      delivered. Reported by "oftc_must_be_destroyed". Fixes bug 7912;
      bugfix on 0.2.0.1-alpha.