Add "gboolean push_undo" parameters to gimp_image_parasite_attach()
and _detach() and use the API also from undo, instead of implementing
attaching/removing manually and forgetting about the signals.
Fixes updating of the image properties color profile page.
We currently have brush and pattern I/O code in both the core and
plug-ins. This commit starts removing plug-in code in favor of having
one copy of the code in the core, much like XCF loading and saving is
implemented.
Add app/file-data/ module with file procedure registering code, for
now just with an implementation of file-gbr-load.
Remove the file-gbr-load code from the file-gbr plug-in.