Moving towards shell library --

François wants me to break the various low-level shell functions out of the
showcase script into a set of shell libraries.  Given this, it makes sense to
move the showcase script off to a lib subdirectory for later dissection, and
write showcase script as an active shell script, i.e., a script that actually
*does* something, rather than using the Maven build to activate the script:
after all, all unit tests will be carried out on the shell library files, not
the showcase script.  The only purpose of the showcase script now is to (i)
identify itself, (ii) locate showcase home (so that it can find the shell
library), (iii) load the shell library scripts it needs, and (iv) call the main
function with the showcase home as its only parameter.
Made shell library non-executable --
Started new showcase script and update pom --

I am building the bew showcase script from scratch.  I have modified the pom
accordingly (i.e., disabled unit testing and copying file set instead of single
file.)
Added intro comments to showcase script --
Added basic showcase home discovery to script --
Strengthened showcase home detection in script --
Started valid function name library --
Completed valid variable lib and tests --
Tidied script slightly --
Added library sourcing loop to script --
Unified handling of shell errors in script --
Split names set variable off into own lib --
Improved test text and assertions --
Completed names set variable script and test --
Completed natural number lib and test --
Added list dir content lib and tests --
Removed dead wood from library --
Updated package POM to pack new script and libs --
Completed solicit choice lib and unit tests --
Completed print choice lib and unit tests --