Make sure that every highest peak value is drawn

As process is usually called more often than
update_cb, we should store the highest peak
value until it is consumed by update_cb.

mixer/src/Meter_Indicator_Module.C

@@ -183,6 +183,7 @@ Meter_Indicator_Module::update_cb ( void )
             for ( int i = 0; i < dpm_pack->children(); ++i )
             {
                 ((DPM*)dpm_pack->child( i ))->value( control_value[i] );
+                control_value[i] = -70.0f;
             }
         }
     }
@@ -275,7 +276,9 @@ Meter_Indicator_Module::process ( nframes_t )
 
         for ( int i = 0; i < p->hints.dimensions; ++i )
 	  {
-            control_value[i] = ((float*)control_input[0].buffer())[i];
+              float dB = ((float*)control_input[0].buffer())[i];
+              if ( dB > control_value[i])
+                  control_value[i] = dB;
 	  }
     }
 }

mixer/src/Meter_Module.C

@@ -89,7 +89,10 @@ Meter_Module::update_cb ( void )
     Fl::repeat_timeout( METER_UPDATE_FREQ, update_cb, this );
 
     for ( int i = dpm_pack->children(); i--; )
+    {
         ((DPM*)dpm_pack->child( i ))->value( control_value[i] );
+        control_value[i] = -70.0f;
+    }
 }
 
 bool
@@ -212,7 +215,8 @@ Meter_Module::process ( nframes_t nframes )
             float dB = 20 * log10( get_peak_sample( (float*)audio_input[i].buffer(), nframes ) );
 
             ((float*)control_output[0].buffer())[i] = dB;
-            control_value[i] = dB;
+            if (dB > control_value[i])
+                control_value[i] = dB;
         }
     }
 }