doc: updated README
build: raised version and updated changelog
stream: use a default backlog size of 511

Kernels usually round it up to the next power of 2, that is, 512. More
on this: http://blog.dubbelboer.com/2012/04/09/syn-cookies.html
doc: update documentation on Stream.listen
build: updated changelog
core: drop support for Python 2.6

So long, and thanks for all the fish.
common: fix compilation warning
doc: update README
style: use consistent naming for internal functions / callbacks
test: add test which ignores exceptions in a excepthook
core: fix subclassing Loop

When Loop was subclassed, Subclass.default_loop() still returned a Loop
instance, even if it wasn't created before. This patch fixes that.

The avid readed may have noticed that this patch also removes the atexit
handler which decref'd the default loop. Upon reading the documentation,
it turns out is not safe to use any Python APIs at that stage, we just
never got bitten by it until now, by chance.
core: raised libuv revision
fs: adapt to API changes in uv_fs_readdir
process: give better error message on Process.close