Start adding support for more leaf cameras

I've started to support more MOS (and IIQ) format cameras from Leaf. There are three new cases:

* a little-endian version of the basic MOS format that's working fine (aptusII-5)
* several LJpeg cameras that don't work with the current LJpeg code (all the other aptus cameras)
* a few cameras that use a specific encoding and need special tiff parsing (the credo's and the ixr). These are not working but I did lift the specific code from dcraw and left it there for future reference

I've gotten a file for each of the cameras for testing at: 

http://pedrocr.pt/leaf/ 

Here is a per-camera breakdown:

* aptus22: works fine, the original camera I had an example file for
* aptusII-10: "Out of buffer read" in the LJpeg code
* aptusII-10R: "LJpegDecompressor: Quantized components not supported."
* aptusII-12: "LJpegDecompressor: Quantized components not supported."
* aptusII-5: added support in this pull request
* aptusII-7: "Out of buffer read" in the LJpeg code
* aptusII-8: "Corrupt JPEG data: bad Huffman code:17"
* credo40: requires the PhaseOneC decoding and specific tiff parsing code
* credo60: requires the PhaseOneC decoding and specific tiff parsing code
* credo80: requires the PhaseOneC decoding and specific tiff parsing code
* ixr: requires the PhaseOneC decoding and specific tiff parsing code

Klaus, do you want to have a look at the LJpeg stuff? As for the special tiff parsing do you want to have a look at dcraw (parse_phase_one) and tell me if normal tiff parsing can be used or if I should just write a one-off parser? I tried parsing it with TiffIFD but it didn't work.