Update copyright year.
Minor comment addition.
Don't ask for user input if user can't respond.
Refactor in preparation for adding report variable calculation

This stringification is logically separate from the data munging.
This removes some code duplication, but more importantly paves the way
to allow it's reuse in the upcoming report variable calculation.
Remove "Reporting Variables" from solution.

Fixes #13.  Sort of.

I suppose I could still incorporate this script automatically into a
post-process section, but for now, it's required to manually execute it.
For example:

    $ ./temoa.py  utopia.dat  |  ./temoa.py  --calculate_report_variables -
       # or
    $ ./temoa.py  utopia.dat > utopia.sol
    $ ./temoa.py --calculate_report_variables utopia.sol > utopia_extended.sol

So, still not ideal, and as #13 states, could lead to a mismatch, but
better than nothing as larger problems will not run much faster in the
Pyomo stage.  "Don't let 'perfect' be the enemy of 'good'."

The astute observer will note that some previously implemented pieces
are no longer implemented, like InvestmentByTech.  That's pending as
round two of this needs to pull in certain details from parameters.
Automatically calculate reporting variables.

On second thought, let's do this correctly now.  Temoa now automatically
calculates the reporting variables at the end of each run, and
delineates them as such in the output solution file.  Consequently,
there's no more need for the --calcul... command line argument.