gui: improve score colors

Mix the base color with the score color in order to have a result that
matches the user's color theme. E.g. on a dark theme the background of
trained entries will appear dark as well, allowing us to use the default
font color to display entries details.

src/gui/EntryDelegate.cc

@@ -88,9 +88,7 @@ void EntryDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option,
 		else textColor = option.palette.color(QPalette::Active, QPalette::HighlightedText);
 	}
 	else {
-		// If the entry is trained, the background color is fixed because we know the background color
-		if (entry->trained()) textColor = Qt::black;
-		else textColor = option.palette.color(QPalette::Text);
+		textColor = option.palette.color(QPalette::Text);
 	}
 
 	// Draw the background

src/gui/EntryFormatter.cc

@@ -35,8 +35,14 @@ static QFont printFont = QFont("", 14);
 QColor EntryFormatter::scoreColor(const Entry &entry)
 {
 	int sc = entry.score() * 5;
-	return QColor(sc > 0xff ? sc < 0x1ff ? 0xff - (sc - 0x100) : 0x00 : 0xff,
-	      sc < 0xff ? sc : 0xff, 0x00).lighter(165);
+	static const float r = 0.3;
+	QColor base(QPalette().color(QPalette::Base));
+	QColor score(QColor(sc > 0xff ? sc < 0x1ff ? 0xff - (sc - 0x100) : 0x00 : 0xff,
+	      sc < 0xff ? sc : 0xff, 0x00).lighter(165));
+
+	return QColor(base.red() * (1 - r) + score.red() * r,
+		      base.green() * (1 - r) + score.green() * r,
+		      base.blue() * (1 - r) + score.blue() * r);
 }