Import(/export) flight plans in the route tool

[Corsac]

Hi, not sure it's really the right place but since the MP route tool is derived from the ME I think it might.

Would it be possible to improve the import/export possibilities for the flight plans in the MP route tool? Examples of quality-of-life improvements:

• in the F10 map, beeing able to import another plane flight plan in the route tool: if you click on a plane you can see its current flight plan, it'd be nice to be able to directly import it from the UI (so only the package leader would create the flight plan)
• support for a `RouteToolPreset\Map` directories with one flight plan per file (so it's easier to share them)
• support for an "export to file" / "import from file" in the route tool (similar)