fix crash when a qkeyevent's text() is empty
fix crash when a qkeyevent's text() is empty

svn path=/trunk/KDE/kdelibs/kate/; revision=874179

DickJ/kate,hlamer/kate,hlamer/kate,sandsmark/kate,hlamer/kate,cmacq2/kate,cmacq2/kate,jfmcarreira/kate,DickJ/kate,cmacq2/kate,jfmcarreira/kate,hlamer/kate,hlamer/kate,sandsmark/kate,jfmcarreira/kate,hlamer/kate,sandsmark/kate,hlamer/kate,hlamer/kate,hlamer/kate,DickJ/kate,hlamer/kate,DickJ/kate,sandsmark/kate