This is briefly moving us over to my fork of pydcs while we wait for
https://github.com/pydcs/dcs/pull/206 to be merged. The adaptation is
invasive enough that I don't want it lingering for long.
Test cases:
1. Target is not threatened.
The IP should be placed on a direct heading from the origin to the
target at the max ingress distance, or very near the origin airfield
if the airfield is closer to the target than the IP distance.
2. Unthreatened home zone, max IP between origin and target, safe
locations available for IP.
The IP should be placed in LAR at the closest point to home.
3. Unthreatened home zone, origin within LAR, safe locations available
for IP.
The IP should be placed near the origin airfield to prevent
backtracking more than needed.
4. Unthreatened home zone, origin entirely nearer the target than LAR,
safe locations available for IP.
The IP should be placed in LAR as close as possible to the origin.
5. Threatened home zone, safe locations available for IP.
The IP should be placed in LAR as close as possible to the origin.
6. No safe IP.
The IP should be placed in LAR at the point nearest the threat
boundary.
