Use lua for special level files

Game is playable, and should compile on linux and Windows.
Assumes you have a lua 5.3 library available.

Removes level compiler and associated files.
Replaces special level des-files with lua scripts.
Exposes some NetHack internals to lua:
 - des-table with commands to create special levels
 - nh-table with NetHack core commands
 - nhc-table with some constants
 - u-table with some player-specific data (u-struct)
 - selection userdata

Adds some rudimentary tests.

Adds new extended command #wizloadlua to run a specific script,
and #wizloaddes to run a specific level-creation script.

nhlib.lua is loaded for every lua script.

Download and untar lua:
  mkdir lib
  cd lib
  curl -R -O http://www.lua.org/ftp/lua-5.3.5.tar.gz
  tar zxf lua-5.3.5.tar.gz

Then make nethack normally.

dat/soko2-1.lua

@@ -0,0 +1,67 @@
+-- NetHack 3.6	sokoban.des	$NHDT-Date: 1432512784 2015/05/25 00:13:04 $  $NHDT-Branch: master $:$NHDT-Revision: 1.13 $
+--	Copyright (c) 1998-1999 by Kevin Hugo
+-- NetHack may be freely redistributed.  See license for details.
+--
+des.level_init({ style = "solidfill", fg = " " });
+
+des.level_flags("mazelevel", "noteleport", "premapped", "solidify");
+
+des.map([[
+--------------------
+|........|...|.....|
+|.....-..|.-.|.....|
+|..|.....|...|.....|
+|-.|..-..|.-.|.....|
+|...--.......|.....|
+|...|...-...-|.....|
+|...|..|...--|.....|
+|-..|..|----------+|
+|..................|
+|...|..|------------
+--------            
+]]);
+des.stair("down", 06,10);
+des.stair("up", 16,04);
+des.door("locked", 18,08);
+des.region(selection.area(00,00, 19,11), "lit");
+des.non_diggable(selection.area(00,00,19,11));
+des.non_passwall(selection.area(00,00,19,11));
+
+-- Boulders
+des.object("boulder",02,02)
+des.object("boulder",03,02)
+--
+des.object("boulder",05,03)
+des.object("boulder",07,03)
+des.object("boulder",07,02)
+des.object("boulder",08,02)
+--
+des.object("boulder",10,03)
+des.object("boulder",11,03)
+--
+des.object("boulder",02,07)
+des.object("boulder",02,08)
+des.object("boulder",03,09)
+--
+des.object("boulder",05,07)
+des.object("boulder",06,06)
+
+-- Traps
+des.trap("hole",08,09)
+des.trap("hole",09,09)
+des.trap("hole",10,09)
+des.trap("hole",11,09)
+des.trap("hole",12,09)
+des.trap("hole",13,09)
+des.trap("hole",14,09)
+des.trap("hole",15,09)
+des.trap("hole",16,09)
+des.trap("hole",17,09)
+
+-- Random objects
+des.object({ class = "%" });
+des.object({ class = "%" });
+des.object({ class = "%" });
+des.object({ class = "%" });
+des.object({ class = "=" });
+des.object({ class = "/" });