master v20201220.7

Continuous integration build 2259, based on Superbuild 20201219.

Major Changes:

• 🌍 KMZ (ground overlay) support for export, import and templates (GH-138, GH-1793)
• Re-added missing "datumgrid" files for precise georeferencing (GH-1802)
• Minor OCD format improvements, including a fix for a crash (GH-1796)
• Template data saving improvements:
  • Atomic scribble template saving (GH-1785)
  • Error reporting for template saving (GH-1790)
  • Template saving working for all file formats (GH-1791)
• List all geospatial vector data export formats explicitly (GH-1779)
• Consistent GPX track positioning (regression, GH-1709)

All changes since master v20201026.1