Execnet

--------------------------------

- add gw.reconfigure() to configure per gateway options. Currently supported:
py2str_as_py3str and py3str_as_py2str to configure string deserialization

- channel.makefile() objects now have a isatty() returning False

- group.allocate_id(spec) allows to early-determine an (automatic) id

- internal refactorings and cleanups (thanks Ronny Pfannschmidt):
- refactor message types into received handler functions
- refactor b(chr(opcode)) to bchr(opcode)
- reorder Message ctor args, rename msgtype to msgcode
- refactor gateway.send to take message's init args instead of a message
- inline and remove Message.writeto/readfrom
- refactor collection loading to avoid the indirection over tuple
- remove the unused NamedThreadPool

--------------------------------

- new ``gateway.remote_exec(func, **kwargs)`` style for executing
a pure function with parameters. The function on the remote
side also needs to accept a ``channel`` which allows it to
communicate back and forth. Thanks to Ronny Pfannschmidt
for implementing it with special kudos to Maciej Fijalkowski
for writing a "pure-function" checker so that on Python2.6
onwards non-pure functions will be rejected.

- enhance rsyncing to also sync permissions (stat().st_mode)
of directories and files.
(should also resolve http://bitbucket.org/hpk42/py-trunk/issue/68/)

- fix rsyncing of symlinks, thanks to Charles Solar
(should also resolve http://bitbucket.org/hpk42/py-trunk/issue/70/)

- update internal usage of apipkg to 1.0b6

- remote_exec(module) now makes sure that the linecache is updated
before reading and sending the source. thanks Ronny, Matt.

- removed all trailing whitespace from source files

--------------------------------

- try to avoid a random KeyboardInterrupt Error when threads
are ending.

- extend xspec syntax to allow for one or multiple "env:NAME=value"
environment variable settings which will be set on the remote side.
(thanks Jakub Gustak)

--------------------------------

- fix jython/windows interactions
- fix waitclose/callback-with-endmarker race condition
- fix race condition where multiple threads sending data over channels
would crash the serializer and process

--------------------------------

- more care during receiver-thread finalization during interp-shutdown,
should get rid of annoying and meaningless exceptions
- fix glitch in ssh-fileserver example
- experimentally add "setup.py test" support - will run py.test

--------------------------------

- try to deal more cleanly with interpreter shutdown setting globals to
None. this avoids (hopefully) some bogus tracebacks at process exit.