Ability to import previews from raw images to Image Sequence

Please add ability to load jpeg previews from *.CR2 and *.ARW images in image sequence (no true raw processing needed). This is useful for making drafts from timelapse shots.

I found that very simple patch will do this:

diff --git a/src/project/dialogs/slideshowclip.cpp b/src/project/dialogs/slideshowclip.cpp
index 8c22d7fa9..36b8f3b8e 100644
--- a/src/project/dialogs/slideshowclip.cpp
+++ b/src/project/dialogs/slideshowclip.cpp
@@ -54,6 +54,8 @@ SlideshowClip::SlideshowClip(const Timecode &tc, QString clipFolder, ProjectClip
     m_view.image_type->addItem(QStringLiteral("TIF (*.tif)"), QStringLiteral("tif"));
     m_view.image_type->addItem(QStringLiteral("TIFF (*.tiff)"), QStringLiteral("tiff"));
     m_view.image_type->addItem(QStringLiteral("Open EXR (*.exr)"), QStringLiteral("exr"));
+    m_view.image_type->addItem(QStringLiteral("Preview from CR2 (*.cr2)"), QStringLiteral("cr2"));
+    m_view.image_type->addItem(QStringLiteral("Preview from ARW (*.arw)"), QStringLiteral("arw"));
     m_view.animation->addItem(i18n("None"), QString());
     m_view.animation->addItem(i18nc("Image Pan", "Pan"), QStringLiteral("Pan"));
     m_view.animation->addItem(i18n("Pan, low-pass"), QStringLiteral("Pan, low-pass"));