Closer to basic functionality.

Cleaned up HTML code. User input now works. Some of the math works.
Displaying every Second-to-last Odometer reading DOES NOT work.  "k"
variable steps is out of the .length of the Database; it works perfectly
to step us through the Last Odometer reading AND the last Gallons,
though. Calculating every Miles Per Gallon works, except when we step
out of the Second-to-last Odometer reading.
Added more comments.