Fixes bug #6660

(Asheviere still standing at the end of the scenario), by manually
[kill]ing her in the die events.

data/campaigns/Heir_To_The_Throne/scenarios/26_Battle_for_Wesnoth.cfg

@@ -299,6 +299,11 @@
 		image="wesnoth-icon.png"
 		message= _ "Li'sar strikes a killing blow!"
 		[/message]
+		[kill]
+			description=Asheviere
+			animate=no
+			fire_event=no
+		[/kill]
 	[/event]
 	[event]
 	name=die
@@ -341,6 +346,11 @@
 		image="wesnoth-icon.png"
 		message= _ "Konrad strikes a killing blow!"
 		[/message]
+		[kill]
+			description=Asheviere
+			animate=no
+			fire_event=no
+		[/kill]
 	[/event]
 	[event]
 	name=die
@@ -423,6 +433,11 @@
 		[sound]
 		name=lightning.ogg
 		[/sound]
+		[kill]
+			description=Asheviere
+			animate=no
+			fire_event=no
+		[/kill]
 		[colour_adjust]
 		red=100
 		green=100
@@ -448,6 +463,11 @@
 		name="main_menu_new.ogg"
 		immediate=yes
 		[/music]
+		[kill]
+			description=Asheviere
+			animate=no
+			fire_event=no
+		[/kill]
 		[message]
 		description=Delfador
 		message= _ "And so passes Asheviere, the dark queen of Wesnoth."