Remove unused sounds, interior and exterior sound

FGData/AI/Aircraft/Aerotow/C-47/Sound/sound.xml

@@ -2,11 +2,39 @@
 <PropertyList>
     <fx>
         <engine>
-            <name>engine</name>
+            <name>engineINT</name>
+            <mode>looped</mode>
+            <path>Croisiere_int_2.wav</path>
+            <condition>
+				<and>
+					<property>/addons/by-id/org.flightgear.addons.Aerotow/addon-devel/sound/enable</property>
+					<property>/sim/current-view/internal</property>
+				</and>
+            </condition>
+            <volume>
+                <offset>-0.80</offset>
+            </volume>
+            <pitch>
+                <property>velocities/true-airspeed-kt</property>
+                <factor>0.012</factor>
+                <offset>0.3</offset>
+                <min>0.3</min>
+                <max>1.0</max>
+            </pitch>
+            <reference-dist>150.0</reference-dist>
+            <max-dist>5000.0</max-dist>
+        </engine>
+		<engine>
+            <name>engineEXT</name>
             <mode>looped</mode>
             <path>Croisiere_ext_2.wav</path>
             <condition>
+				<and>
 					<property>/addons/by-id/org.flightgear.addons.Aerotow/addon-devel/sound/enable</property>
+					<not>
+						<property>/sim/current-view/internal</property>
+					</not>
+				</and>
             </condition>
             <volume>
                 <offset>-0.80</offset>