Lots of UI updates

[patudom]

Big stuff (in the commit called "Coordinate sun tracking & centering UI")

With Jon's #41 update to allow tracking off center, we needed to coordinate the switches and offer the user a way to center back on the Sun. It ended up being way more complicated than I thought it would be, and I'm not sure my changes are bulletproof, but everything seems to behave how I intended it to. It would be good if someone could please check and make sure everything makes sense. I had to delete/disable some things where I was not 100% sure what they were meant to do, and it's possible I left in things or added things that are not really necessary. This is what I intended:

• If user is tracking Sun (toggleTrackSun = true), we need to make sure that tracking is active whether we are centered on the Sun (trackSun) or not centered (trackSunOffset).
• If user is not tracking Sun, we should not be doing either trackSun or trackSunOffset
• If Sun is centered and tracking (sunCenteredTracking = true), disable but check the "Center Sun" box. (I disable it because it doesn't make sense to be able to uncheck the "Center Sun" box because it's not like we can pick a random point to send them to, now that centering & tracking are 2 separate things).
• If Sun is not centered or if we are not tracking the Sun, the Center Sun box is unchecked and can be checked to bring the sun back to center and begin tracking again.
• I added a thing called activePointer because while I was mousing down and panning around in WWT, the sun tracking toggle would automatically change itself to off, so I only try to set trackingSun if activePointer = false.

Smaller stuff

• Remove SunScope mode (and always stay in Horizon Mode). Feedback is that it was confusing users.
• Remove corresponding documentation related to SunScope mode
• With Sun offset tracking #41, we can track without being centered, so documentation now just refers to "tracking Sun" rather than "center on sun"
• Make sure all 3 white chips fit across screen on mobile. (We disable the cloud cover chip on desktop because it appears prominently in the cloud info box anyway).
• Describe what the cloud cover chip is for in the documentation
• Link to other SciAct eclipse resources