Explicitly use WSASocketW, as WSASocketA has been deprecated.

Fixes boost trac ticket #10534.
Fix warnings reported by VS2013.

Fixes boost trac ticket #10376.
Add lazy kqueue EVFILT_WRITE registration.

This fixes support for read-only file descriptors, such as those
obtained from libpcap by calling pcap_get_selectable_fd.

Fixes boost trac ticket #10367.
Fix shadow variable warnings.
Specify additional headers that don't have a convenience header.

Fixes boost trac ticket #10567.
Use correct type in byte order conversion of shorts.

Fixes boost trac ticket #10539.
Deregister EVFILT_WRITE to avoid spinning with serial ports.

Fixes boost trac ticket #10496.
Make all kqueue event registration lazy.

Fixes the kqueue reactor so that it works on FreeBSD again.

Fixes boost trac ticket #10606.
Fix compile error in /dev/poll reactor.

Fixes boost trac tickets #10350, #10572.