Fix wrong sign, found while reading code.

This was not a problem as both values iwidth and iheight were divided.
Minor code clean-up.
rawspeed: Nikon Coolpix P7100 blackpoint fix (thanks to nesthib)
ICC profile handling: catch certain mal-formatted profiles

some profiles claim to have color locus information for red, green and blue
base colors available, but in fact these are all set to zero (e.g. my Canon camera
profiles). We need to let these profiles be handled by lcms2 as we can't derive a valid
color matrix.
usermanual: more docs on module "unbreak input profile"
Olympus E-M5 enhanced matrix with help from Frederic Crozat
Update to rawspeed r514 (thanks Klaus)
usermanual: update on lighttable panel "history stack"
Merge branch 'master' of ssh://github.com/darktable-org/darktable
Merge branch 'lightroom'

* lightroom:
  Minor code clean-up.
  Fix wrong sign, found while reading code.
bug prevention : if a format has not specified a dimension, default to unlimited size instead of uninitialized value