* app/edit_selection.c: removed some nonfunctional code.
* app/paint_core.c: remove the alt toggles perfectmouse behaviour.
* app/paintbrush.c: when ctl (or alt) is held set the fg (or bg) color.
* app/gimpparasite.[ch]: made char *name parameters const.
* app/parasitelist.c: removed unused static variable.
* app/gimpdrawable.c, app/gimpimage.c, app/undo.[ch]: added
support for undoing parasite changes.
* libgimp/gimp.h, libgimp/gimpimage.c: added
gimp_undo_push_group_start and gimp_undo_push_group_end
* libgimp/parasite.[ch]: added undoable flag.
* plug-ins/gdyntext/font_selection.c: fixed c++ style comment.
* plug-ins/gdyntext/gdyntext.c: use the new undoable parasites.
* plug-ins/rcm/rcm_misc.c: arctg can't be inline because it is
used in other .c files
* plug-ins/waterselect/waterselect.c,
* plug-ins/rotators/rotators.c, app/tips_dialog.c, app/plug_in.c:
fixed some warnings