Add support for C&C Covert Ops music (fixes half of #824).

OpenRA.Game/GameRules/MusicInfo.cs

@@ -21,9 +21,11 @@ namespace OpenRA.GameRules
 
 		public MusicInfo( string key, MiniYaml value )
 		{
-			Filename = key+".aud";
 			Title = value.Value;
 
+			var nd = value.NodesDict;
+			var ext = nd.ContainsKey("Extension") ? nd["Extension"].Value : "aud";
+			Filename = (nd.ContainsKey("Filename") ? nd["Filename"].Value : key)+"."+ext;
 			if (!FileSystem.Exists(Filename))
 				return;
 			

mods/cnc/music.yaml

@@ -1,23 +1,51 @@
 aoi: Act on Instinct
+aoi2: Act on Instinct (Voiced)
+	Filename: aoi
+	Extension: var
 airstrik: Air Strike
+befeared: Be Feared
+befeared2: Be Feared (Voiced)
+	Filename: befeared
+	Extension: var
+80mx226m: C&C 80's mix
 ccthang: C&C Thang
 ind2: Canyon Chase
+chrg226m: Charge
+crep226m: Creep
 stopthem: Deception
 heavyg: Demolition
+die: Die
+dril225m: Drill
+dron226m: Drone
 fwp: Fight Win Prevail
+fist226m: Fist
+warfare: Full Stop
 win1: Great Shot!
+win2: Great Shot! (Voiced)
+	Filename: win2
+	Extension: var
+heart: Heartbreak (Voiced)
+	Extension: var
+iam: I am (Voiced)
 ind: Industrial
 linefire: In the Line of Fire
-justdoit: Just do it!
-trouble: Looks like Trouble
+trouble: In Trouble
+trouble2: In Trouble (Voiced)
+	Filename: trouble
+	Extension: var
+justdoit: Just do it up!
 map1: Map Theme
 march: March to Doom
-target: Mechanical Man
 nomercy: No Mercy
 otp: On the Prowl
 prp: Prepare for Battle
 radio: Radio
 rain: Rain in the Night
+rout: Reaching out (Voiced)
+	Extension: var
+recn226m: Recon
 jdi_v2: Take em' out
+target: Target
 j1: Untamed Land
-warfare: Warfare
+valkyrie: Ride of the Valkyries
+voic226m: Voices