Allow the user to cancel rearrangements of tool order and visibility in Preferences. See enhancement request/bug #500930.
- split up button callbacks into one callback per button - add stephen to copyright - some minor whitespace fixups
Rename gimptoolview.[ch] to gimptooleditor.[ch]. The contents of the file has already gone through this change, we do the file name change separately for better diffs. Part of fix for bug #500930.
