Add support for a configurable compass declination in a range of -99 to 99 degrees. This allows the displayed compass reading to be configured to take into account the compass declination (difference between the measured magnetic North direction and the actual geographical North direction) that has different values for different locations around the globe. See https://magnetic-declination.com/ for more information. (mikeller)

Heinrichs Weikamp OSTC4 update files.

The builds are for testing purposes only. Be careful, they might not work and are definitely not recommended for real dives.