Extend zmq::wsa_error_to_errno()

The list of error codes is taken from zmq::wsa_error_no(). Most of the
new WSA error codes result in EFAULT, but some return a more specific
value (even EAGAIN).

Backport of zeromq/libzmq#1072
Merge pull request #83 from olafmandel/backport_1072

Extend zmq::wsa_error_to_errno()
Fix failed assertion for WSAENOTSOCK

In de9eef306, the error number assigned to WSAENOTSOCK was EFAULT, but
zmq.cpp:919 expects an ENOTSOCK in this case.
Merge pull request #84 from hintjens/master

Fix failed assertion for WSAENOTSOCK
Fixed typo in doc example
Merge pull request #86 from hintjens/master

Fixed typo in doc example