refine.py: add ability to look at different indicators depending on guardian…

This merge request allows use of different indicators channels for refine.py depending on the previous guardian state, implementing the ideas mentioned in #9 (closed).

It appears to work well for a variety of different lock losses that it wasn't able to refine before, for various guardian states.

Another thing it does it fixes a bug where refine.py would wrongly state that the refined time was past the guardian time lock loss specified, because it is using the integer GPS time for the lock loss, but the actual time of the lock loss could be up to a second after this time. Now it will compare against the time of the loss and see whether the refinement actually does better than before.

Closes #9 (closed).

Some examples:

Before	After