BUGFIX: Fix minor compilation issues added from the new changes.

Improved subjugation mechanics so, rather than having to substantially destroy an empire to force subjugation leaving them largely useless, you need a military victory they can't come back from. (Specifically, they'll consider it hopeless if you have twice as many flagships and a total military strength 5x theirs).
Removed AI becoming agitated with empires getting too many point. They only get agitated for valid reasons, and not for meta-game reasons.
Alliances are far more resistant to breaking while engaging an enemy now.
Relationship with an empire is now much more important to treaty acceptance chances, where before it had very little bearing.
Empires will now offer peace if substantially outmatched (2x their military strength), allowing one to feasibly have a series of wars due to multiple disputes or shifting priorities rather than locking one into a conflict until one side or the other is subjugated or extinct.

Fixed another bug where donations might be cited as the cause for breaking an alliance, and made greatly outmatched empires prefer to remain in an unhappy alliance over breaking it.
EDIT: Also reintroduced a bias towards 0 from the *negative* direction, so an unhappy empire that's not at war may cool off if there's no interaction at all.

Diplomatic standing no longer has a slight bias towards returning to 0 (neutral).
Reduced penalty for bordering an empire from -15 to -10.
Reduced bonus for having a larger military from +15 to +10, keeping it in line with bordering.

Intended change is that border disputes will slowly escalate to a hot war if it's advantageous (if the AI has a larger military than the other party) or will simmer if not unless stoked by outside factors (don't start a full-scale war over semi-trivial disputes with someone you expect to lose to unless given a good reason). In addition, it's intended that relations "stick" a bit more, so good relations with an empire imply ongoing good relations without requiring strategic-level maintenance.