greentest.py: reimplement switch counting without relying on setUp/tearDown. disable switch counting for now since it more gets in a way than points out problems

move gevent.fileobject.ignore_errors into gevent.os.ignored_errors; do not call _map_errors where unnecessary; make gevent.os.read/write ignore EINTR (it's useless for gevent apps) and EINVAL on darwin (issue #148)

--HG--
rename : greentest/test_os.py => greentest/test__os.py

As a benign side-effect, if read or write is interrupted with EINTR, hub.wait() will be
called before calling read/write again. (previously read/write was called immediatelly)

thanks temoto!

commit.

This initial implementation contains cooperative read() and write(),
and also moves fork() from gevent.hub to gevent.os.

This patch prepares for the addition of a "gevent.os" module.

--HG--
rename : util/make_dist.py => util/makedist.py

use copy instead of os.link since the latter might fail for various reasons

testrunner.py rewrite: remove stat printing functionality; store more data in db; more reliable killing of subprocesses