allow setting of pixel format/ocio method/sample format in preferences

Implementation isn't perfect yet, viewer/renderer doesn't update yet when
the preference is changed so a sequence needs to be re-opened for the change to
take effect.

app/render/pixelservice.cpp

@@ -25,11 +25,22 @@
 #include <QFloat16>
 
 #include "common/define.h"
+#include "core.h"
 
 PixelService::PixelService()
 {
 }
 
+PixelFormat::Format PixelService::GetConfiguredFormatForMode(RenderMode::Mode mode)
+{
+  return static_cast<PixelFormat::Format>(Core::GetPreferenceForRenderMode(mode, QStringLiteral("PixelFormat")).toInt());
+}
+
+void PixelService::SetConfiguredFormatForMode(RenderMode::Mode mode, PixelFormat::Format format)
+{
+  Core::SetPreferenceForRenderMode(mode, QStringLiteral("PixelFormat"), format);
+}
+
 PixelFormat::Info PixelService::GetPixelFormatInfo(const PixelFormat::Format &format)
 {
   PixelFormat::Info info;