do not reset highlight compression when doing histogram matching

rtengine/improccoordinator.cc

@@ -459,7 +459,6 @@ void ImProcCoordinator::updatePreviewImage (int todo, Crop* cropCall)
             params.toneCurve.brightness = 0;
             params.toneCurve.contrast = 0;
             params.toneCurve.black = 0;
-            params.toneCurve.hlcompr = 0;
 
             if (aeListener) {
                 aeListener->autoMatchedToneCurveChanged(params.toneCurve.curveMode, params.toneCurve.curve);

rtengine/simpleprocess.cc

@@ -753,7 +753,6 @@ private:
             params.toneCurve.brightness = 0;
             params.toneCurve.contrast = 0;
             params.toneCurve.black = 0;
-            params.toneCurve.hlcompr = 0;
 
         }        
 

rtgui/tonecurve.cc

@@ -567,7 +567,9 @@ void ToneCurve::adjusterChanged (Adjuster* a, double newval)
         return;
     }
 
-    setHistmatching(false);
+    if (a != expcomp && a != hlcompr && a != hlcomprthresh) {
+        setHistmatching(false);
+    }
     
     Glib::ustring costr;