removed some nonfunctional code.
* 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