The four remaining "classic" color tools (Brightness-Contrast, Curves,
Levels and Threshold) are in fact just special UIs for otherwise
completely normal filter ops.
Add normal filter actions for them and invoke them like all
other filters, which makes them show up in the filter history
automatically.
The only small hack needed is to special case them in
gimp_gegl_procedure_execute_async() so the right tools are created
instead of the default GimpOperationTool. Also, blacklist the
automatically generated tools actions from action search and the
shortcut editor.
...and present linear RGB Histograms
This is step one: implement the feature at all (without new defaults
or proper GUI, cough).
Add boolean "linear" properties to GimpOperationPointFilter,
GimpCurvesConfig and GimpLevelsConfig.
In the filter, simply set the input/output formats to linear in
prepare().
In the curves and levels tools, add "Linear" toggles from hell,
like in the histogram dockable, and make sure things work right
wrt changing and resetting the property, switching from levels
to curves, and picking colors.
The result currently changes when switching a non-nop curves/levels
between perceptual and linear, because adjusting the parameters
between the spaces is not implemented yet.
- don't include <gdk-pixbuf/gdk-pixbuf.h> in headers in app/
- instead, include it in many .c files instead of <glib-object.h>,
finally acknowledging the fact that app/ depends on gdk-pixbuf almost
globally
- fix up includes as if libgimpbase depended in GIO, which it soon will
