Support teleporting to offline players

The YCTIWY mod is already keeping track of offline player
positions, so allow admins to use those for teleportation.  This
is sort of like the szutil_offlinepos mod, but as a standard
game feature now.  It can be useful for admins to quickly locate
players who are trapped and need rescue, or suspected of griefing
and need to be confirmed.

mods/nc_player_yctiwy/init.lua

@@ -90,6 +90,39 @@ local function savestate(player)
 	db[player:get_player_name()] = ent
 end
 
+------------------------------------------------------------------------
+-- TELEPORT COMMAND
+
+local teleport = minetest.registered_chatcommands.teleport
+if teleport and teleport.func then
+	local cannot = nodecore.translate("Cannot teleport an offline player.")
+	local oldfunc = teleport.func
+	teleport.func = function(caller, ...)
+		local oldget = minetest.get_player_by_name
+		local function helper(...)
+			minetest.get_player_by_name = oldget
+			return ...
+		end
+		function minetest.get_player_by_name(name, ...)
+			local player = oldget(name, ...)
+			if player then return player end
+			local s = db[name]
+			if s and s.pos then
+				return {
+					get_pos = function() return s.pos end,
+					set_pos = function()
+						minetest.after(0, function()
+								return minetest.chat_send_player(caller, cannot)
+							end)
+					end,
+					get_attach = function() end,
+				}
+			end
+		end
+		return helper(oldfunc(caller, ...))
+	end
+end
+
 ------------------------------------------------------------------------
 -- MISC/UTILITY/COMMON