bin/ysh is the shell with data tYpes, influenced by pYthon, JavaScript, ...

Usage: ysh FLAG* SCRIPT ARG*
       ysh FLAG* -c COMMAND ARG*
       ysh FLAG*

`bin/ysh` is the same as `bin/osh` with a the `ysh:all` option group set.  So
`bin/ysh` also accepts shell flags.

    ysh -c 'echo hi'
    ysh myscript.ysh
    echo 'echo hi' | ysh
