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.

rtexif/pentaxattribs.cc

@@ -1228,6 +1228,7 @@ public:
         choices[2]    = "HDR 1";
         choices[3]    = "HDR 2";
         choices[4]    = "HDR 3";
+        choices[5]    = "Advanced";
 
         choices1[0]   = "Auto-align Off";
         choices1[1]   = "Auto-align On";