Magic-wormhole

* the server can now "blur" usage information: this turns off HTTP logging,
and rounds timestamps to coarse intervals
* `wormhole server usage` now shows Transit usage too, not just Rendezvous

* `wormhole` can now send/receive entire directories. They are zipped before
transport.
* Python 3 is now supported for async (Twisted) library use, requiring at
least Twisted-15.5.0.
* A bug was fixed which prevented py3-based clients from using the relay
transit server (not used if the two sides can reach each other directly).
* The `--output-file=` argument was finally implemented, which allows the
receiver to override the filename that it writes. This may help scripted
usage.
* Support for Python-2.6 was removed, since the recent Twisted-15.5.0 removed
it too. It might still work, but is no longer automatically tested.
* The transit relay now implements proper flow control (Producer/Consumer),
so it won't buffer the entire file when the sender can push data faster
than the receiver can accept it. The sender should now throttle down to the
receiver's maximum rate.

* Add key-confirmation message so "wormhole send" doesn't hang when the
receiver mistypes the code.
* Fix `wormhole send --text -` to read the text message from stdin. `wormhole
receive >outfile` works, but currently appends an extra newline, which may
be removed in a future release.
* Arrange for 0.4.0 senders to print an error message when connecting to a
current (0.5.0) server, instead of an ugly stack trace. Unfortunately 0.4.0
receivers still display the traceback, since they don't check the welcome
message before using a missing API. 0.5.0 and 0.6.0 will do better.
* Improve channel deallocation upon error.
* Inform the server of our "mood" when the connection closes, so it can track
the rate of successful/unsuccessful transfers. The server DB now stores a
summary of each transfer (waiting time and reported outcome).
* Rename (and deprecate) one server API (the non-EventSource form of "get"),
leaving it in place until after the next release. 0.5.0 clients should
interoperate with both the 0.6.0 server and 0.6.0 clients, but eventually
they'll stop working.

* Change the CLI to merge send-file with send-text, and receive-file with
receive-text. Add confirmation before accepting a file.
* Change the remote server API significantly, breaking compatibility with
0.4.0 peers. Fix EventSource to match W3C spec and real browser behavior.
* Add py3 (3.3, 3.4, 3.5) compatibility for blocking calls (but not Twisted).
* internals
* Introduce Channel and ChannelManager to factor out the HTTP/EventSource
technology in use (making room for WebSocket or Tor in the future).
* Change app-visible API to allow multiple message phases.
* Change most API arguments from bytes to unicode strings (appid, URLs,
wormhole code, derive_key purpose string, message phase). Derived keys are
bytes, of course.
* Add proper unit tests.

* listen on IPv4+IPv6 properly (16)

* listen on IPv4+IPv6 socket by default (16)
* deallocate AppNamespace objects when empty (12)
* add client-version-uptake munin plugin
* drop support for py3.3 and py3.4