The new Shellfu brings some large changes.  Among what touches us
directly:

 *  Most global variables were renamed (removing SHELLFU_* prefix).

 *  inigrep API has been revamped and the file merging/guessing
    feature has been dropped; it now belongs to us.

Scripts may need it (eg. if using `saturnin__runhook()`) but exporting
it in the middle of main script makes it harder to see the scope
clearly and also is ugly.

Tweak the saturnin__runsc syntax so that it's not dependent on this
being global and export the SATURNIN_SUBCOMMAND only for the actual
subcommand binary call.

Makes it easier to grok the structure and keep the global space clean.

Order does not matter, therefore use canonical order to simplify updates.

Use of app name when naming of global variables and/or mkit tokens makes
upgrade of the saturnin template painful and error-prone, while none of
these variables can be overriden from environment so the namespacing
advantage is vain.

Since saturnin's dedication to be "meta-command" builder, the distinction
between "meta" and something else does not make much sense.

The routines are all basically related to the meta-command functions.

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.

Add checks for syntax errors and missing SATURNIN_SUBCOMMAND.  In both
cases, ignore the hook.

Minimize the "built part" and code repetition among saturnin "clones".

To allow for experimenting with functions from embedded library.

This should help test and manage embedded Fastfoo library

 *  Add docstring,
 *  add explanations for local variable names,
 *  separate export declarations,
 *  sort globals alphabetically,
 *  add built part delimiters,
 *  quote paths properly.

... turns out it's faster (surprise! ;))

Due to inigrep limitation, we cannot automatically cherry-pick hook.ini
based on where the hook is found--we can only have all hooks in one
file, or use join strategy.

Add section like this to hook.ini:

    [hook.mycomm]
        pre = echo $SATURNIN_SUBCOMMAND will run soon
        pre = echo $SATURNIN_SUBCOMMAND is almost running
        post = echo $SATURNIN_SUBCOMMAND has finished now

"@" breaks the string to several arguments, which is not what we want
here