moved WindowClosingHandler to AppWapplication; setLabels in LanguageGUI

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@37248 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
renamed from cancel to delete

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@37249 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
don't use separator if there's only one entry

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@37250 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e