This really needs to be a proper type, but this is a start: create new
categories for the types of TGOs that are missing. This removes some
icon special cases.
* A Bluefor EWR 55GS in the campaign miz defines an optional EWR site. There is no distinction between how close or far it is to a base, so it's possible that there will be many EWRs within an airbase.
* A Redfor EWR 1L13 in the campaign miz defines a required EWR site.
It would be a good future idea to limit the amount of EWRs within a certain distance from an airbase. That way there's no chance of 5 EWRs all at the same airbase. Even better if there were something preventing any two EWRs from being right next to each other.
No campaigns take advantage of this yet.
Fixes https://github.com/Khopa/dcs_liberation/issues/524
