New command allows to define flexible menus in INI files.
Single INI root now contains all menu definitons. Each menu consists of
item generator, selector and consumer, which are checked and chained
together.
Alternatively to specifying a generator, items can be listed right in
the INI section.
This module is intended to be moved around with saturnin, but unlike
main meta-command (bin/saturnin.skel), it should not be necessary to
rename it or edit to adapt to new project.