Add freespace 1 style missile behavior

[Baezon]

Though the source code for freespace 1 is not available, using some comments and lots of testing by Goober, a fairly convincing facsimile of it can be approximated. The main eventual algorithm (-1x lag pursuit, starting at 1 second out) ended up both quite close to the observed behavior and is rather simple and involves minimal changes from the existing code, making it a likely contender for what they used.

Also included are a few other observed miscellaneous changes to free flight time, the missile's speed, and early detonation conditions.

Freespace 1:

fs1q.mp4

FSO, with this flag active:

2025-03-08_21-11-35.mp4

For reference, by default in Freespace 2, aspect seekers fly a nearly dead-on straight path, following a 1x lead pursuit the whole time, none of this wiggling S shape.

[JohnAFernandez]

Good thing it was nice and simple. Just a request to add a comment as it's not immediately clear what that branch is doing.

[MjnMixael]

Not sure if possible but I'd think this would be something more useful as a weapon flag rather than a profiles flag so certain weapons could use it and others not. Kinda like swarm, corkscrew, etc.

[Baezon]

Not sure if possible but I'd think this would be something more useful as a weapon flag rather than a profiles flag so certain weapons could use it and others not. Kinda like swarm, corkscrew, etc.

If you really think it would be useful, it would be possible, but I definitely was not thinking it would be useful to anyone. I went into this purely with the idea it'd be a compatibility flag, just to make behavior match fs1 closer, not because anyone would actually desire this behavior. It's really really bad and certainly unintuitive behavior, I can't imagine any modder actually wanting 'yes please make my missile completely veer off target a second before impact to practically guarantee it will miss'.

My imagination shouldn't be the only arbiter, so if you still think so, I will, but I do want to make it clear this is bad and weird behavior imo lol

[MjnMixael]

Not sure if possible but I'd think this would be something more useful as a weapon flag rather than a profiles flag so certain weapons could use it and others not. Kinda like swarm, corkscrew, etc.

If you really think it would be useful, it would be possible, but I definitely was not thinking it would be useful to anyone. I went into this purely with the idea it'd be a compatibility flag, just to make behavior match fs1 closer, not because anyone would actually desire this behavior. It's really really bad and certainly unintuitive behavior, I can't imagine any modder actually wanting 'yes please make my missile completely veer off target a second before impact to practically guarantee it will miss'.

My imagination shouldn't be the only arbiter, so if you still think so, I will, but I do want to make it clear this is bad and weird behavior imo lol

To be clear, I have no current plans with this, but it looked to be a potential tool in the toolbelt. You know my most prominent FSO project is BtA and that project tries to bridge the gap between "old & busted" and "new & shiny", especially as it applies to technology progression. To that end, finding ways to make certain weapons behave intentionally poorly is something we've actually done. I can't say for sure we'd use this as plans for BtA3's gameplay are really just in the very early stages.

[Baezon]

Alright, that's fair enough.

[Goober5000]

This PR is immediately useful as a balance tool for FSPort and other missions converted from FS1 missions. An AI profiles flag is perfect because it simply changes the balance context, rather than requiring extensive modifications to weapons and ship loadouts. I wouldn't be opposed to a weapon flag that does the same thing though.

Just a few code comments.

[Baezon]

Yeah, I'm doing both flags.