Make color of timing markers themable

src/Cfg.cpp

@@ -71,6 +71,7 @@ void ColorTheme::load(BuiltInColorTheme builtInColorTheme)
         playingZoneMiddle  = CColor(0.0f, 0.0f, 0.4f);
         playingZoneBorder  = CColor(0.0f, 0.0f, 0.8f);
         textColor          = CColor(0.0, 0.0, 0.0);     // black
+        timingMarkerColor  = textColor;
         break;
     default:
         *this = ColorTheme();

src/Cfg.h

@@ -105,6 +105,7 @@ struct ColorTheme
     CColor playingZoneMiddle  = CColor(0.0f, 0.0f, 0.8f);
     CColor playingZoneBorder  = CColor(0.0f, 0.0f, 0.6f);
     CColor textColor          = CColor(1.0f, 1.0f, 1.0f);
+    CColor timingMarkerColor  = CColor(1.0f, 1.0f, 1.0f);
 };
 
 /*!

src/Draw.cpp

@@ -788,7 +788,7 @@ void CDraw::drawSymbol(CSymbol symbol, float x, float y, CSlot* slot)
         {
             auto pianistX = static_cast<float>(symbol.getPianistTiming());
             pianistX =  x + pianistX * HORIZONTAL_SPACING_FACTOR;
-            drColor(CColor(1.0, 1.0, 1.0));
+            drColor(colorTheme.timingMarkerColor);
             glLineWidth (2.0f);
             glBegin(GL_LINES);
             glVertex2f( 4.0f + pianistX, 4.0f + y);