AR calibration reference

[kylecorry31]

Allow the user to choose what to calibrate with when they click the calibrate button.

• [ ] Sun
• [ ] Moon
• [ ] Beacon (prompts the user to pick a beacon)
• [ ] Adjust wording of instruction message to refer to the "reference point" instead of Sun/Moon

In the future this could also include calibration using a known star.

By default select either the sun or the moon depending on if it is day or night (current behavior).