GitLab

  * Add `Terms` section with a bunch of definitions
  * Add section `File and directory structure`
  * Remove some old notes

Index rebuilding is not a feature this program is going to have.

We're going to use base-36 IDs.

Rationale: The legacy version of `mote` is currently at 0.27.0. So, to avoid
overlapping version numbers between the Bash version and the Ada rewrite, and
because a rewrite (in the 0.x.y phase) definitely warrants incrementing the
minor version,

  * the version number of the Ada rewrite is changed to 0.28.0
  * beginning with 0.28.0, version numbers of the legacy "branch" will carry
    the suffix `-legacy`

For reasons to be explained elsewhere, the new `Show_Help` function has been
limited to printing a usage summary.