Add multi-frame handling.

- Exif of all frames are displayed in the Editor's Exif tab (without
separator)
- isHDR and isPixelShift is added to the data files stored in cache
- In the Editor panel, the QuickInfo frame display the HDR and
PixelShift information, as well as the number of frame and bit-depth for
HDR image
- the number of frame is provided by dcraw. If not set, it is provided
by the Exif's main IFD count
- the PixelShift information (for Pentax as of now) is provided by
looking at the Exif informations
- the HDR information is provided by the Exif information of the first
frame for Pentax raw files, or by the bitspersample, sampleformat and
compression tags for other files

TODO: add icons to the thumbnails to tag HDR and PixelShift files.

rtgui/cacheimagedata.h

@@ -21,6 +21,7 @@
 
 #include <glibmm.h>
 #include "options.h"
+#include "../rtengine/imageformat.h"
 
 class CacheImageData
 {
@@ -51,6 +52,9 @@ public:
     double focalLen, focalLen35mm;
     float focusDist;
     unsigned iso;
+    int isHDR;  // null if no HDR, otherwise provide the number of frame for this HDR file
+    bool isPixelShift;
+    rtengine::IIO_Sample_Format sampleFormat;
     Glib::ustring lens;
     Glib::ustring camMake;
     Glib::ustring camModel;