[cpp] Cleaned up parsing of dark slot colors. See #1090

spine-cpp/spine-cpp/src/spine/SkeletonBinary.cpp

@@ -176,7 +176,7 @@ SkeletonData *SkeletonBinary::readSkeletonData(const unsigned char *binary, cons
 		unsigned char b = readByte(input);
 		unsigned char a = readByte(input);
 		if (!(r == 0xff && g == 0xff && b == 0xff && a == 0xff)) {
-			slotData->getDarkColor().set(r / 255.0f, g / 255.0f, b / 255.0f, 0);
+			slotData->getDarkColor().set(r / 255.0f, g / 255.0f, b / 255.0f, 1);
 			slotData->setHasDarkColor(true);
 		}
 		slotData->_attachmentName.own(readString(input));

spine-cpp/spine-cpp/src/spine/SkeletonJson.cpp

@@ -223,7 +223,7 @@ SkeletonData *SkeletonJson::readSkeletonData(const char *json) {
 				darkColor.r = toColor(dark, 0);
 				darkColor.g = toColor(dark, 1);
 				darkColor.b = toColor(dark, 2);
-				darkColor.a = toColor(dark, 3);
+				darkColor.a = 1;
 				data->setHasDarkColor(true);
 			}