The previous flight plan only makes sense if the convoy will make it a
significant distance from its starting point. At road speeds over the
typical mission duration this is not true, so we can actually plan this
as if it was a strike mission near the origin point and that's close
enough.
There's some cleanup work to do here that I've added todos for.
Fixes https://github.com/Khopa/dcs_liberation/issues/996
50d8e08a34