Updates to SCANsat.cs

Fixes for science data storage, transmission, saving/loading
Unclutter OnUpdate

Probably needs more testing, but seemed ok when I checked it. These are mostly the methods that I use for my plugins, so they should work.

OnUpdate had some unnecessary code, I put some of it in OnInitialize (the last thing to run on startup) and made dedicated methods for registering/deregistering sensors.

I think there are still some scattered references to the old scope scanner in other files that should probably be removed in addition to the ones I took out here.