Move private req and handle fields to platform headers

And fix other problems introduced with UV_HANDLE_TYPE_MAP and UV_REQ_TYPE_MAP.
Add functions to look up req and handle sizes

Useful for FFI bindings. Closes #370.
Windows: backport pipe-connect-to-file fixes from master

Conflicts:

    src/win/pipe.c


commit e53ab6675ba12d97ad6d93c9913a473ba5172617
Author: Bert Belder <bertbelder@gmail.com>
Date:   Fri Mar 9 17:04:03 2012 +0100

    Windows: report UV_ENOTSOCK when we opened a file instead of a pipe

    Makes the pipe_connect_to_file test pass on Windows.

commit 8cbbfbe4c6489868470a7e410f80d4729f4091bf
Author: Igor Zinkovsky <igorzi@microsoft.com>
Date:   Thu Mar 1 14:32:59 2012 -0800

    test: make pipe_connect_to_file succeed with ECONNREFUSED

commit 6bbccf1fe0e000fd73e945368466cd27291483e3
Author: Igor Zinkovsky <igorzi@microsoft.com>
Date:   Thu Mar 1 12:11:12 2012 -0800

    windows: return UV_ENOTSOCK when doing uv_pipe_connect to a file
Windows: don't report ENOTSOCK when attempting to bind an udp handle twice
Merge branch 'v0.6'
Revert "Fix memory leak in uv_exepath() on OSX."

This reverts commit f6c8e78db973a0f57424dba74c97fdd4d2f910f8.

realpath() on OS X 10.5 crashes if resolved_path == NULL.
add 64bit offset fs functions
unix: add missing function declaration
unix: fix compiler warning, #include <unistd.h>
unix: add uv_fs_read64, uv_fs_write64 and uv_fs_ftruncate64
unix: don't conditionally compile kqueue fs watcher

Always compile in the kqueue-based fs event watcher and handle it at run-time
if the kernel doesn't actually support it.

Works around build issues when -mmacosx-version-min is not set properly.

Fixes joyent/node#3075.
unix: fix udp_options test on OS X and Solaris

setsockopt(IP_TTL) will happily let you set a TTL > 255 on OS X, cap it.

-1 or 0 is a valid TTL on Linux but not portable, deny it.
Tests: don't use %zu placeholder in printf statements

It's not supported by msvcrt.
test: disable fs_event_close_in_callback on kqueue-based systems
Whitespace
Add UV_EIO error code
Disable ipc_send_recv_pipe test on Windows

It's not supported yet
unix: run pending shutdown cb when stream is closed
Windows: validate UDP socket options

Makes test-udp-options pass on Windows.
Windows: make uv_uptime() more robust