SPU:

* support channel repeat mode 3, behaves same as mode 1 (loops)
* always clear channel buffers, so if channels 0-7 use format 3, they don't output old data over and over again (fixes #281)

src/SPU.h

@@ -121,6 +121,9 @@ public:
 
     void DoRun(s32* buf, u32 samples)
     {
+        for (u32 s = 0; s < samples; s++)
+            buf[s] = 0;
+
         switch ((Cnt >> 29) & 0x3)
         {
         case 0: Run<0>(buf, samples); break;