SVY-6882 shortcuts mechanism

almost all shortcuts are directly catched in eclipse already (and are
working on selection) so for that not much has to be done
(undo/redo,cut/copy/paste)
select-all sometimes also works in the browser (and in eclipse) so that
one is disabled in the editor (glasspane is constantly focussed because
of this)
DEL key is special, eclipse has special code that keybindings do not
work on text,combo and browser components, so that one only can be
catched in the browser