Change the way camXyz is discovered, and fixes

- When camXyz is not provided by LibRaw, try to read it from metadata or calculate from rgbCam (experimental).
- Always save the ColorMatrix1 tag, even if it is only the identity matrix, to adhere to the standard.
- Save the X-Trans pattern like the other patterns. This is the correct way, the problem is in DCRaw.
- Calculate auto white balance like DCRaw.