Added days 12, 13 & 14

Was too busy to commit them earlier.

Sadly, with an end-of-year project at work, I believe that these are
the last ones I’m likely to get to work on this year, at least in
time.  I’m pretty bummed — it’s been great fun so far.
Add day 10

It was pretty awesome seeing the message print out!
Add day 9

I’m really proud of the fact that I thought about the problem,
implemented the solutions and got the correct answers, each time.
Add day 8

Easy as pie!
Add day 7

For some reason, today was unreasonably difficult.  I clearly need to
spend some more time working with & thinking about graphs.
Solutions for day 2
Reformat lines to fit in 80 columns
Reformat comment line