Make a menu of buffers so you can manipulate buffers or the buffer list.
Uses keymap `bs-mode-map', which is not currently defined.
There are many key commands similar to `Buffer-menu-mode' for
manipulating the buffer list and the buffers themselves.
User can move with [up] or [down], select a buffer
by M-x bs-select or [SPC]
Type M-x bs-kill to leave Buffer Selection Menu without a selection.
Type M-x bs-help after invocation to get help on commands available.
With prefix argument ARG show a different buffer list. Function
`bs--configuration-name-for-prefix-arg' determine accordingly name of buffer configuration. (fn ARG)