Feature request: export .gpx files

In Mission Planner when you convert log->kmz it also writes a .gpx file, which is needed in a lot of GIS or 3rd party orthorectification/stitching software. The format is trivial.

So alongside 'Log to Google Earth File', could we also have 'Log to GPX File'?

If you're worried about a proliferation of buttons there, perhaps just one called 'Convert Log' or 'Export Log' which brings up an export dialog with format options (including Droneshare?), which also allows a good extension point for any other formats or portals we might want to add on later.

Start by locating the existing “Log to Google Earth File” conversion entry point in the Qt desktop application and trace how log-to-KMZ export is handled. The issue leaves the separate-button versus export-dialog choice open; done means a user can export the log as a valid .gpx file, with any chosen format menu or dialog integrated with the existing export flow.

Written by the indexing model from the issue text.