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.

 *  Use proper naming scheme
 *  Rename saturnin_meta module

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

E.g.: ` bz 1234` should now work the same as `bz 1234`.