Began marking changes for monsters

These changes include storing monsters on shutdown, storing dead
characters and monsters, etc. Also fleshed out the MonsterManager's
internals a bit.

(cherry picked from commit af982710f6de050c09ef503cf2f8e1c9fdd34979)

server/network_api.cpp

@@ -62,8 +62,13 @@ static int pumpCharacterUpdate(lua_State* L) {
 	return 1;
 }
 
+static int pumpMonsterUpdate(lua_State* L) {
+	//TODO: (0) send the info about a specific monster instance
+}
+
 static const luaL_Reg networkLib[] = {
 	{"PumpCharacterUpdate", pumpCharacterUpdate},
+	{"PumpMonsterUpdate", pumpMonsterUpdate},
 	{nullptr, nullptr}
 };