Fixed: Use lua_tointeger under Lua 5.2 and prior versions

--HG--
branch : develop

code/nel/include/nel/gui/lua_helper_inline.h

@@ -253,7 +253,9 @@ inline lua_Integer CLuaState::toInteger(int index)
 {
 	//H_AUTO(Lua_CLuaState_toInteger)
 	checkIndex(index);
+#if LUA_VERSION_NUM >= 503
 	sint isnum = 0;
+	// lua_tointeger fails with decimal numbers under Lua 5.3
 	lua_Integer res = lua_tointegerx(_State, index, &isnum);
 	if (!isnum)
 	{
@@ -262,6 +264,9 @@ inline lua_Integer CLuaState::toInteger(int index)
 		res = (lua_Integer)d;
 	}
 	return res;
+#else
+	return lua_tointeger(_State, index);
+#endif
 }
 
 //================================================================================