rawspeed for fuji x-series cameras

- update dngmeta.sh to read 6x6 CFA -- this code could also work for
  2x2 CFAs, though currently each has its own path
- patch rawspeed to handle 14 bpp RAF files -- this may not work in
  all cases, needs more testing
- pre-rotate matrix when load image
- add x-series cameras support in cameras.xml (when in doubt use crops
  as reported in raw file rather than from observation)

White/black levels and crop may differ from libraw version.
document different behavior for x-trans sensors
cleaner edges for Markesteijn demosaic

Make a mirrored/interpolated extra border to give algorithm room to
work. Thank you to Lars Kotthoff for the idea! This version uses more
memory and is slightly slower, but worth it to help the top tier
algorithm do a good job on edges with a lot of detail.