New sling sounds

Patch by: @Samulis
This was SVN commit r24874.

binaries/data/mods/public/art/actors/props/units/weapons/sling.xml

@@ -14,7 +14,7 @@
     </variant>
     <variant frequency="0" name="attack_ranged">
       <animations>
-        <animation event="0.5" file="mechanical/weap_sling_attack.dae" name="attack_ranged" id="attack_ranged_01" speed="100"/>
+        <animation event="0.5" sound="0.1" file="mechanical/weap_sling_attack.dae" name="attack_ranged" id="attack_ranged_01" speed="100"/>
       </animations>
       <mesh>props/weap_sling_attack.dae</mesh>
     </variant>

binaries/data/mods/public/art/variants/biped/attack_ranged_slinger.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <variant name="attack_ranged">
   <animations>
-    <animation event="0.50" file="biped/infantry/slinger/attack_ranged.dae" load="0.75" name="attack_ranged" id="attack_ranged_01" speed="100"/>
+    <animation event="0.50" sound="0.1" file="biped/infantry/slinger/attack_ranged.dae" load="0.75" name="attack_ranged" id="attack_ranged_01" speed="100"/>
   </animations>
   <props>
     <prop actor="props/units/weapons/sling.xml" attachpoint="weapon_R"/>

binaries/data/mods/public/audio/attack/weapon/sling_attack.xml

@@ -19,4 +19,5 @@
 	<Sound>sling_attack_03.ogg</Sound>
 	<Sound>sling_attack_04.ogg</Sound>
 	<Sound>sling_attack_05.ogg</Sound>
+	<Sound>sling_attack_06.ogg</Sound>
 </SoundGroup>