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.
(cherry picked from commit 710cfc1f47)
but only the actual saving code, not the export magic and dialog.
Add new internal procedure file-pat-save-internal which is not
registered as a file procedure and always works non-interactively on
the passed arguments and only saves the passed drawable. Use the new
internal procedure from the file-pat-save code and remove all file
writing code from the plug-in.
This way all pattern file writing code duplication is killed, while
the whole export mechanism is completely unchanged.
(cherry picked from commit b29ecfb5da)
