[gimp] (6 commits) Non-fast-forward update to branch wip/pippin

[Øyvind Kolås <ok src gnome org>]

The branch 'wip/pippin' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  b24e58b... app: make levels config request linear colors
  fd41922... app: make curves tool pick in linear
  931e37e... operations: make levels and curves operate on linear data
  3e96d01... app: default many created gimp_histograms to linear
  ef59d04... app: hide advanced color options
  3f05c51... app: do promotion to float by default in default settings

Commits added to the branch:

  81eb91c... app: do promotion to float by default in default settings
  6d012dd... app: make levels config request linear colors
  38afec4... app: make curves tool pick in linear
  b059ea4... operations: make levels and curves operate on linear data
  2b4fe8a... app: default many created gimp_histograms to linear
  6f25900... app: hide advanced color options