Lua: nhcore script with function callbacks

Adds possible callbacks for "start_new_game", "restore_old_game",
"moveloop_turn", and "game_exit" which when defined, will be called
from core code at the appropriate time.

Adds lua hooks for dump_fmtstr (only if DUMPLOG), dnum_name, u.moves,
u.uhave_amulet, and u.depth.

include/decl.h

@@ -995,6 +995,9 @@ struct instance_globals {
     int lusername_size;
 #endif
 
+    /* nhlua.c */
+    genericptr_t luacore; /* lua_State * */
+
     /* o_init.c */
     short disco[NUM_OBJECTS];
 

include/extern.h

@@ -1657,6 +1657,9 @@ extern int l_obj_register(lua_State *);
 /* ### nhlua.c ### */
 
 #if !defined(CROSSCOMPILE) || defined(CROSSCOMPILE_TARGET)
+extern void l_nhcore_init(void);
+extern void l_nhcore_done(void);
+extern void l_nhcore_call(int);
 extern lua_State * nhl_init(void);
 extern void nhl_done(lua_State *);
 extern boolean nhl_loadlua(lua_State *, const char *);

include/hack.h

@@ -421,6 +421,16 @@ typedef struct sortloot_item Loot;
 #define SUPPRESS_HISTORY 4
 #define URGENT_MESSAGE   8
 
+/* Lua callback functions */
+enum nhcore_calls {
+    NHCORE_START_NEW_GAME = 0,
+    NHCORE_RESTORE_OLD_GAME,
+    NHCORE_MOVELOOP_TURN,
+    NHCORE_GAME_EXIT,
+
+    NUM_NHCORE_CALLS
+};
+
 /* Macros for messages referring to hands, eyes, feet, etc... */
 enum bodypart_types {
     ARM       =  0,