There is no way to add other suffix for library loading

[Takashi Kato]

It would be convenient if users can add additional library file's suffix. (e.g .sld)

2 things need to be done;

1. sash's command line option (analogy of '-L' option)
2. programmatic way to add (analogy of add-load-path)

[Takashi Kato]

Added add-load-suffix Added -S option