SL(1): Cure your bad habit of mistyping

SL (Steam Locomotive) runs across your terminal when you type "sl" as you meant to type "ls". It's just a joke command, and not useful at all.

Update notes from eyJhb

I have merged the following

I have also added -v and updated the last updated and version number to 5.04.

Name		Name	Last commit message	Last commit date
Latest commit History 47 Commits
.gitignore		.gitignore
LICENSE		LICENSE
Makefile		Makefile
README.ja.md		README.ja.md
README.md		README.md
demo.gif		demo.gif
sl.1		sl.1
sl.1.ja		sl.1.ja
sl.c		sl.c
sl.h		sl.h