Use CriticalSection in audio source. Add bool argument for seek to get immediate seeks. etc

Source/PS_Source/Input/InputS.h

@@ -50,7 +50,7 @@ public:
 				nsmps-=readsize;
 			};
 		};
-		virtual void seek(double pos)=0;//0=start,1.0=end
+		virtual void seek(double pos, bool immediate)=0;//0=start,1.0=end
 
 		struct {
 			int64_t nsamples=0;