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/rawmetadatalocation.h

@@ -22,11 +22,19 @@
 namespace rtengine
 {
 
-struct RawMetaDataLocation {
+class RawMetaDataLocation {
+
+public:
     int exifBase;
     int ciffBase;
     int ciffLength;
+
+    RawMetaDataLocation () : exifBase(-1), ciffBase(-1), ciffLength(-1) {}
+    RawMetaDataLocation (int exifBase) : exifBase(exifBase), ciffBase(-1), ciffLength(-1) {}
+    RawMetaDataLocation (int ciffBase, int ciffLength) : exifBase(-1), ciffBase(ciffBase), ciffLength(ciffLength) {}
+    RawMetaDataLocation (int exifBase, int ciffBase, int ciffLength) : exifBase(exifBase), ciffBase(ciffBase), ciffLength(ciffLength) {}
 };
+
 }
 
 #endif