sdt/3.5

• support for lowmem machine.
• add 'url_replace' selection file parameter.
• add 'http_fallback' option (switch protocol on error).
• add 'default_listing_size' configuration option.
• add '-m' option to 'synda remove command'.
• add 'check' action for selection file.
• add 'check' action for file's variable.
• add new 'open' action.
• add 'default_path' option in sdt.conf.
• bugfixes and ergonomy improvement.