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/bigrm-4.lua

@@ -0,0 +1,43 @@
+
+des.level_init({ style = "solidfill", fg = " " });
+des.level_flags("mazelevel");
+
+des.map([[
+-----------                                                     -----------
+|.........|                                                     |.........|
+|.........|-----------|                             |-----------|.........|
+|-|...................|----------|       |----------|...................|-|
+  -|.............................|-------|.............................|-  
+   -|.................................................................|-   
+    -|...............................................................|-    
+     -|.............................................................|-     
+      -|...........................................................|-      
+      -|...........................................................|-      
+     -|.............................................................|-     
+    -|...............................................................|-    
+   -|.................................................................|-   
+  -|.............................|-------|.............................|-  
+|-|...................|----------|       |----------|...................|-|
+|.........|-----------|                             |-----------|.........|
+|.........|                                                     |.........|
+-----------                                                     -----------
+]]);
+
+des.region(selection.area(01,01,73,16), "lit");
+
+des.stair("up");
+des.stair("down");
+
+des.non_diggable();
+
+for i = 1,15 do
+   des.object();
+end
+
+for i = 1,6 do
+   des.trap();
+end
+
+for i = 1,28 do
+  des.monster();
+end