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.

dat/nhcore.lua

@@ -0,0 +1,74 @@
+
+-- This file contains lua code used by NetHack core.
+-- Is it loaded once, at game start, and kept in memory until game exit.
+
+
+-- This is an example of generating an external file during gameplay,
+-- which is updated periodically.
+-- Intended for public servers using dgamelaunch as their login manager.
+local prev_dgl_extrainfo = 0;
+function mk_dgl_extrainfo()
+    if ((prev_dgl_extrainfo == 0) or (prev_dgl_extrainfo + 50 < u.moves)) then
+        local filename = nh.dump_fmtstr("/tmp/nethack.%n.%d.log");
+        local extrai, err = io.open(filename, "w");
+        if extrai then
+            local sortval = 0;
+            local dname = nh.dnum_name(u.dnum);
+            local dstr = "";
+            local astr = " ";
+            if u.uhave_amulet == 1 then
+                sortval = sortval + 1024;
+                astr = "A";
+            end
+            if dname == "Fort Ludios" then
+                dstr = "Knx";
+                sortval = sortval + 245;
+            elseif dname == "The Quest" then
+                dstr = "Q" .. u.dlevel;
+                sortval = sortval + 250 + u.dlevel;
+            elseif dname == "The Elemental Planes" then
+                dstr = "End";
+                sortval = sortval + 256;
+            elseif dname == "Vlad's Tower" then
+                dstr = "T" .. u.dlevel;
+                sortval = sortval + 235 + u.depth;
+            elseif dname == "Sokoban" then
+                dstr = "S" .. u.dlevel;
+                sortval = sortval + 225 + u.depth;
+            elseif dname == "The Gnomish Mines" then
+                dstr = "M" .. u.dlevel;
+                sortval = sortval + 215 + u.dlevel;
+            else
+                dstr = "D" .. u.depth;
+                sortval = sortval + u.depth;
+            end
+            local str = sortval .. "|" .. astr .. " " .. dstr;
+
+            extrai:write(str);
+            extrai:close();
+        else
+            -- failed to open the file.
+            nh.pline("Failed to open dgl extrainfo file: " .. err);
+        end
+        prev_dgl_extrainfo = u.moves;
+    end
+end
+
+
+-- Callback functions
+nhcore = {
+    -- start_new_game called once, when starting a new game
+    -- after "Welcome to NetHack" message has been given.
+    -- start_new_game = function() nh.pline("NEW GAME!"); end,
+
+    -- restore_old_game called once, when restoring a saved game
+    -- after "Welcome back to NetHack" message has been given.
+    -- restore_old_game = function() nh.pline("RESTORED OLD GAME!"); end,
+
+    -- moveloop_turn is called once per turn.
+    -- moveloop_turn = mk_dgl_extrainfo,
+
+    -- game_exit is called when the game exits (quit, saved, ...)
+    -- game_exit = function() end,
+};
+