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/Val-loca.lua

@@ -0,0 +1,85 @@
+-- NetHack 3.6	Valkyrie.des	$NHDT-Date: 1553807172 2019/03/28 21:06:12 $  $NHDT-Branch: NetHack-3.6.2-beta01 $:$NHDT-Revision: 1.15 $
+--	Copyright (c) 1989 by Jean-Christophe Collet
+--	Copyright (c) 1991-2 by M. Stephenson
+-- NetHack may be freely redistributed.  See license for details.
+--
+des.level_init({ style = "solidfill", fg = " " });
+
+des.level_flags("mazelevel", "hardfloor", "icedpools")
+
+des.level_init({ style="mines", fg=".", bg="I", smoothed=true, joined=false, lit=1, walled=false })
+
+des.map([[
+PPPPxxxx                      xxxxPPPPPx
+PLPxxx                          xPPLLLPP
+PPP    .......................    PPPLLP
+xx   ............................   PPPP
+x  ...............................  xxxx
+  .................................   xx
+....................................   x
+  ...................................   
+x  ..................................  x
+xx   ..............................   PP
+xPPP  ..........................     PLP
+xPLLP                             xxPLLP
+xPPPPxx                         xxxxPPPP
+]]);
+-- Dungeon Description
+des.region(selection.area(00,00,39,12), "lit")
+-- Stairs
+des.stair("up", 48,14)
+des.stair("down", 20,06)
+-- Non diggable walls
+des.non_diggable(selection.area(00,00,39,12))
+-- Objects
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+des.object()
+-- Random traps
+des.trap("fire")
+des.trap("fire")
+des.trap("fire")
+des.trap("fire")
+des.trap()
+des.trap()
+-- Random monsters.
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("fire ant")
+des.monster("a")
+des.monster({ class = "H", peaceful = 0 })
+des.monster({ id = "fire giant", peaceful = 0 })
+des.monster({ id = "fire giant", peaceful = 0 })
+des.monster({ id = "fire giant", peaceful = 0 })
+des.monster({ id = "fire giant", peaceful = 0 })
+des.monster({ id = "fire giant", peaceful = 0 })
+des.monster({ id = "fire giant", peaceful = 0 })
+des.monster({ id = "fire giant", peaceful = 0 })
+des.monster({ class = "H", peaceful = 0 })
+