Fix failing C++ build tests

Making color a real property type broke the build of tests that compare
color properties. Fix this and the incorrect decoding of
strings in the cast to colors, by providing a proper public C++ color
wrapper type.

api/sixtyfps-cpp/include/sixtyfps_color.h

@@ -0,0 +1,33 @@
+#pragma once
+
+#include "sixtyfps_color_internal.h"
+
+#include <stdint.h>
+
+namespace sixtyfps {
+
+class Color
+{
+public:
+    Color() { inner.red = inner.green = inner.blue = inner.alpha = 0; }
+    explicit Color(uint32_t argb_encoded)
+    {
+        inner.red = (argb_encoded >> 16) & 0xff;
+        inner.green = (argb_encoded >> 8) & 0xff;
+        inner.blue = argb_encoded & 0xff;
+        inner.alpha = (argb_encoded >> 24) & 0xff;
+    }
+
+    friend bool operator==(const Color &lhs, const Color &rhs)
+    {
+        return lhs.inner.red == rhs.inner.red && lhs.inner.green == rhs.inner.green
+                && lhs.inner.blue == rhs.inner.blue && lhs.inner.alpha == rhs.inner.alpha;
+    }
+
+    friend bool operator!=(const Color &lhs, const Color &rhs) { return !(lhs == rhs); }
+
+private:
+    internal::types::Color inner;
+};
+
+}