Writing Exif data to RAW files

[Tobias Leupold]

Hi all,

I now added support for dng, nef and cr2 RAW images. Wasn't too hard ;-)

By default, the geodata is always written to XMP sidecar files. There's also a 
new option to allow writing RAW images ("Allow altering Exif headers of RAW 
images"), along with a warning that this is experimental.

@Angel: Would you be so kind to test the "raw" branch, to see if this works 
the way you would expect it?

Thanks again for all input and help about this, and for all the effort to make 
KGeoTag better :-)

Cheers, Tobias