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.

include/ntconf.h

@@ -284,4 +284,9 @@ extern void FDECL(nhassert_failed, (const char * exp, const char * file,
 #define nethack_enter(argc, argv) nethack_enter_winnt()
 extern void FDECL(nethack_exit, (int)) NORETURN;
 extern boolean FDECL(file_exists, (const char *));
+
+#ifndef SYSTEM_H
+#include "system.h"
+#endif
+
 #endif /* NTCONF_H */