Update to 3.0rc1

* Fix build with lua 5.2.

Changelog:

Main changes for LuaSocket 3.0-rc1 are IPv6 support and Lua 5.2 compatibility.

    * Added: Compatible with Lua 5.2
        - Note that unless you define LUA_COMPAT_MODULE, package
          tables will not be exported as globals!
    * Added: IPv6 support;
        - Socket.connect and socket.bind support IPv6 addresses;
        - Getpeername and getsockname support IPv6 addresses, and
          return the socket family as a third value;
        - URL module updated to support IPv6 host names;
        - New socket.tcp6 and socket.udp6 functions;
        - New socket.dns.getaddrinfo and socket.dns.getnameinfo functions;
    * Added: getoption method;
    * Fixed: url.unescape was returning additional values;
    * Fixed: mime.qp, mime.unqp, mime.b64, and mime.unb64 could
      mistaking their own stack slots for functions arguments;
    * Fixed: Receiving zero-length datagram is now possible;
    * Improved: Hidden all internal library symbols;
    * Improved: Better error messages;
    * Improved: Better documentation of socket options.
    * Fixed: manual sample of HTTP authentication now uses correct
      "authorization" header (Alexandre Ittner);
    * Fixed: failure on bind() was destroying the socket (Sam Roberts);
    * Fixed: receive() returns immediatelly if prefix can satisfy
      bytes requested (M Joonas Pihlaja);
    * Fixed: multicast didn't work on Windows, or anywhere
      else for that matter (Herbert Leuwer, Adrian Sietsma);
    * Fixed: select() now reports an error when called with more
      sockets than FD_SETSIZE (Lorenzo Leonini);
    * Fixed: manual links to home.html changed to index.html (Robert Hahn);
    * Fixed: mime.unb64() would return an empty string on results that started
      with a null character (Robert Raschke);
    * Fixed: HTTP now automatically redirects on 303 and 307 (Jonathan Gray);
    * Fixed: calling sleep() with negative numbers could
      block forever, wasting CPU. Now it returns immediately (MPB);
    * Improved: FTP commands are now sent in upper case to
      help buggy servers (Anders Eurenius);
    * Improved: known headers now sent in canonic
      capitalization to help buggy servers (Joseph Stewart);
    * Improved: Clarified tcp:receive() in the manual (MPB);
    * Improved: Decent makefiles (LHF).
    * Fixed: RFC links in documentation now point to IETF (Cosmin Apreutesei).


(ryoon)