Minor fidgety changes to the galilInterface file (primary adding back some comments that document /why/ stuff is done the way it's done)

A few things.

1. I stuck my old testing-code in the repo, which clutters things up a bit.
2. The download mode is non-interactive, so allowing it to run if `:` chars are received is undesireable. Changed.
3. The empty-line commenting was broken, in non-comment-stripping mode, fixed.