ConsiderAlliesforSoundAlerts
Tracking Issue: #620
Normally units firing weapons alert only their enemies.
This feature allows units to alert their allies as well when they fire.
Note that this will not have any effect unless a mod has turned on
yellow alerts in XComGameState_AIUnitData::ShouldEnemyFactionsTriggerAlertsOutsidePlayerVision(),
since by default alert data is not recorded for sounds outside of XCom's vision.