Packaging: v1.0 Corrections and Additional Updates

[tldahlgren]

This PR makes additional v1.0 corrections and updates, to include:

• add and correct (missing) build system imports in a couple of examples;
• switch stackstart default type from int to str to stop the warnings;
• add leaked to the mpileaks description to match what is currently in the source repository's description;
• change the directory name of the tutorial repository (in packaging.sh) from repos to my_pkgs to be less confusing w.r.t. repository-related commands and ensure consistency with presentation text;
• update packaging.sh to display $HOME where possible (to make copy-and-paste during tutorials easier);
• add a tip on the reason and use of the "project-prepared" tarball for tutorial-mpileaks and provided a link to the ONLY package that actually calls the autogen.sh script;
• cleanup some of the flow and wording (esp. new notes); and
• uncomment/update some of packaging.sh's examples.

[tldahlgren]

Since there are important corrections in this PR and another tutorial coming up quickly, I would rather not let this PR languish. The assumption is the next person giving this tutorial will make updates as needed anyway.