Add config check to disable multitarget red alert on yelling

Better fixes X2CommunityCore#717

Disables the red alert effect at the source instead of just for civilians, so also fixes falling back units, which apparently use this ability too.

X2WOTCCommunityHighlander/Config/XComGame.ini

@@ -273,3 +273,6 @@ bEnableVersionDisplay=true
 ; Uncomment the following line to disable the civilian pre-move yell mechanic
 ; bDisableCivilianPreMoveYell = true
 
+;;; HL-Docs: ref:YellRedAlert
+; Uncomment the following line to disable the yell ability applying a multitarget Red Alert effect to surrounding units.
+; bDisableYellRedAlert = true

X2WOTCCommunityHighlander/Src/XComGame/Classes/CHHelpers.uc

@@ -245,8 +245,9 @@ var config float ProjectileParticleSystemExpirationDefaultOverride;
 // Variable for Issue #817 - put the string here, as UIOptionsPCScreen is native and cannot have new variables.
 var localized string m_strFramerateSmoothingDisabledReason;
 
-// Variable added Issue #717 - allow disabling the civilian pre-move yell
+// Variables added Issue #717 - allow disabling the civilian pre-move yell
 var config bool bDisableCivilianPreMoveYell;
+var config bool bDisableYellRedAlert;
 
 // Start Issue #885
 enum EHLDelegateReturn

X2WOTCCommunityHighlander/Src/XComGame/Classes/X2Ability_AlertMechanics.uc

@@ -322,7 +322,10 @@ static function X2AbilityTemplate AddYellAbility()
 	Template.AbilityToHitCalc = ChanceToActivate;
 
 	//Effect on a successful test is adding the red alert persistent effect to the unit
-	AddRedAlertEffects(Template, true);
+
+	/// HL-Docs: feature:YellRedAlert; issue:717; tags:
+	/// Add config option to the "Yell" ability applying a RedAlert effect to nearby units.  
+	AddRedAlertEffects(Template, !(class'CHHelpers'.default.bDisableYellRedAlert));
 
 	//Trigger on player input.
 	InputTrigger = new class'X2AbilityTrigger_PlayerInput';