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.

Overview of changes:

 *  Maintenance release

...or,

> ...maintain "state of the art" templates by comparing with peer
> projects.

It's easier to maintain "state of the art" templates by comparing with
peer projects.

subcommand (binary) and its arguments are both already is debug-shown
inside saturnin__runsc; cases when that does not get called are normally
not interesting.

Overview of changes:

 *  Added "last git hash" to application version meta-data (--saturnin-get-*)
 *  Improve meta command template
 *  Build system maintenance

Overview of changes:

 *  Changed default cache path to under .cache subdir
 *  Added --saturnin-get-* for printing Saturnin internal info
 *  Simplified test suite a bit with new TFKit
 *  Enabled Debian packaging
 *  Repo maintenance and cleanup

These were accidentally left after creating the test from template.

Overview of changes:

 *  Heavily simplify template maintenance
 *  Update MKit to version v0.0.9
 *  Update MKit packaging meta-data
 *  Add packaging for demo kit
 *  Fix and improve demo kit
 *  Lot of refactoring
 *  Improve docs

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.

Useful for testing saturnin itself

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.