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.

rtengine/stdimagesource.cc

@@ -158,7 +158,7 @@ int StdImageSource::load (const Glib::ustring &fname, int imageNum, bool batch)
 
     embProfile = img->getEmbeddedProfile ();
 
-    idata = new ImageData (fname);
+    idata = new FramesData (fname);
 
     if (idata->hasExif()) {
         int deg = 0;