SID (Sudden Ionospheric Disturbance) Feature

[srcejon]

This PR adds a SID (Sudden Ionospheric Disturbance) Feature. SIDs can occur where there are solar flares, CMEs (Coronal Mass Ejections) and very powerful GRBs (Gamma Ray Bursts). They can be detected by monitoring how the received power of naval VLF transmitters changes. This feature includes a chart for plotting power vs time, as well as images and data from a number of satellites, such as Solar Dynamics Observatory, SOHO, GOES, Fermi and the Solar Orbiter, in order to help determine the cause.

See: https://github.com/srcejon/sdrangel/blob/freq_scanner/plugins/feature/sid/readme.md

Also included:

• Map feature can export data to KML files. Implements AIS and ADSB decoders: improvement proposal #1068
• MUF/foF2 data on map can display data from the last 5 days, not just the current data.
• APRS fixes for APRS igate only forwards packets it can decode #2029 and APRS igate tries to UTF-8 re-encode APRS packets #2028
• KiwiSDR now includes it's GPS location in the Web report.
• Sky Map feature now has a 2D and 3D map of the Moon.
• Channel Power supports absolute frequency setting.
• A few other small bug fixes.