FR: Radar Line of Sight, Complex Radar Signature Mechanics

This feature adds somewhat more complex behavior to the radar, and has implications on AI as well.

Essentially, this will get radar Line of Sight properties, if there's something big (ship, asteroid, station) in between you and another object, the other object won't be as visible on radar.

This conceptually works with a ray-trace algorithm to check if the object is visible or obscured. If it is obscured, then its radar signature value could be decremented by some value to effectively decrease its detection and resolution ranges.

When the signature is "strong" or "normal" its resolved, when the signature is "weak" its unresolved (jittery blips), and "very weak" won't show on radar. The naming here suggests that a fuzzy logic solution may be viable.

Initially this algorithm can be only applied to small craft (fighters, bombers, etc.) and can quickly just ray-trace to the center of the object. For larger objects such as ships and stations the ray-trace can be to each of the corners of its bounding box.

For performance, the signature check could be done at a reasonable rate, such as maybe once per second, instead of checked every frame.