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/filecatalog.cc

@@ -770,6 +770,8 @@ void FileCatalog::previewReady (int dir_id, FileBrowserEntry* fdn)
             if (cfs->focalLen > dirEFS.focalTo) {
                 dirEFS.focalTo = cfs->focalLen;
             }
+
+            //TODO: ass filters for HDR and PixelShift files
         }
 
         dirEFS.filetypes.insert (cfs->filetype);