- it's only used in once place and useless on its own

- wrap_ssl is still available as an alias but will be removed soon

import constants from stdlib's socket into gevent.socket. Thanks to Matt Goodall for the original patch.

- this leads to better error information, esp. with easy_install which suppresses stackrace

- web.py only likes sockets that have _sock property

the former is default now

- although not necessary, it should be there for completeness and for the sake
  of potential alternative implementations of greenlet