Tidying Export Graphics dialog

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@27658 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Redo-undo-Buttons styling

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@27659 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e