Added new script_command for 'timed bonus/script' idea: http://rathena.org/board/topic/72463-suggest-to-add-a-script-command-run-item-script-inside-npc-script/
-- bonus_script "<script code>",<duration>{,<flag>{,<type>{,<char_id>}}};
-- see 'doc/script_commands.txt' for more details.
-- Thank everyone who discussed it

Signed-off-by: Cahyadi Ramadhan Togihon <house.bad@gmail.com>