Add clock_timebase(), clock_set_timebase().

src/sclock.h

@@ -55,11 +55,13 @@ double clock_time( SClock * );
 int    clock_fwd( SClock * );		/* returns +1 (fwd) or -1 (back) */
 int    clock_running( SClock * );
 double clock_speed( SClock * );
+double clock_timebase( SClock * );
 void   clock_set_time( SClock *, double newtime );
 void   clock_set_running( SClock *, int running );
 void   clock_set_fwd( SClock *, int fwd );
 void   clock_set_step( SClock *, double deltatime );
 void   clock_set_speed( SClock *, double speed );
+void   clock_set_timebase( SClock *, double timebase );
 void   clock_set_range( SClock *, double tmin, double tmax, double wrapband );
 void   clock_add( SClock *, double incr );
 void   clock_step( SClock *, double sign );