A user can now modify the existing default loadout, rather than starting from scratch.
Also adds WIP handling for removed pylons, which looks like it may need some PyDCS work.
Also fixes the F-14B default loadouts for everything OTHER than fighter sweep again.
The default loadout is now displayed whenever the custom loadout checkbox is unchecked.
The custom loadout is reset when the custom loadout is checked, to force the user to be prescriptive about the loadout.
Contributes-to: Khopa/dcs_liberation#725
Follow up work:
* Data entry. I plan to do the air-to-air missiles in the near term. I
covered some variants of the AIM-120, AIM-7, and AIM-9 here, but there
are variants of those weapons for each mounting rack that need to be
done still, as well as all the non-US weapons.
* Arbitrary start dates.
https://github.com/Khopa/dcs_liberation/issues/490
Conditional in comprehension appears to be intended to exclude
dunders, but was also excluding many TER weapons from Weapon class args
beginning with '_'
