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/Kni-filb.lua

@@ -0,0 +1,40 @@
+-- NetHack 3.6	Knight.des	$NHDT-Date: 1432512784 2015/05/25 00:13:04 $  $NHDT-Branch: master $:$NHDT-Revision: 1.9 $
+--	Copyright (c) 1989 by Jean-Christophe Collet
+--	Copyright (c) 1991,92 by M. Stephenson
+-- NetHack may be freely redistributed.  See license for details.
+--
+des.level_init({ style = "solidfill", fg = "." });
+
+des.level_flags("mazelevel");
+
+des.level_init({ style="mines", fg=".", bg="P", smoothed=false, joined=true, lit=1, walled=false })
+
+--
+des.stair("up")
+des.stair("down")
+--
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+--
+des.monster({ id = "quasit", peaceful=0 })
+des.monster({ id = "quasit", peaceful=0 })
+des.monster({ id = "quasit", peaceful=0 })
+des.monster({ id = "quasit", peaceful=0 })
+des.monster({ class = "i", peaceful=0 })
+des.monster({ id = "ochre jelly", peaceful=0 })
+des.monster({ id = "ochre jelly", peaceful=0 })
+des.monster({ id = "ochre jelly", peaceful=0 })
+--
+des.trap()
+des.trap()
+des.trap()
+des.trap()