Hopefully it works, since that's untested (I have no MacOS access). This
is mostly code from file-darktable.c, made generic and factorized into
file-raw-utils.[ch]. At least it still builds and work fine on Linux.
I used the CFBundleIdentifier from `tools/osx/Info.plist.in` in
RawTherapee code. I didn't add a Win32 registry key base though, since I
couldn't find any relevant data for this in RawTherapee code.
