Fix auto-indentation for dui editor
Fix auto-indentation for dui editor

This patch should fix auto-indentation (Ctrl+I) for the most usual
cases. Before this patch, lines were never dedented, resulting in e.g.

Rect {
  Item {
    }
    Item {
      }

ostash/qt-creator-i18n-uk,hdweiss/qt-creator-visualizer,xianian/qt-creator,jonnor/qt-creator,farseerri/git_code,xianian/qt-creator,AltarBeastiful/qt-creator,jonnor/qt-creator,Distrotech/qtcreator,martyone/sailfish-qtcreator,azat/qtcreator,omniacreator/qtcreator,sandsmark/qtcreator-minimap,duythanhphan/qt-creator,amyvmiwei/qt-creator,colede/qtcreator,colede/qtcreator,martyone/sailfish-qtcreator,pcacjr/qt-creator,KDE/android-qt-creator,omniacreator/qtcreator,kuba1/qtcreator,hdweiss/qt-creator-visualizer,pcacjr/qt-creator,AltarBeastiful/qt-creator,xianian/qt-creator,kuba1/qtcreator,colede/qtcreator,AltarBeastiful/qt-creator,hdweiss/qt-creator-visualizer,ostash/qt-creator-i18n-uk,yinyunqiao/qtcreator,syntheticpp/qt-creator,richardmg/qtcreator,azat/qtcreator,duythanhphan/qt-creator,martyone/sailfish-qtcreator,farseerri/git_code,xianian/qt-creator,omniacreator/qtcreator,syntheticpp/qt-creator,farseerri/git_code,xianian/qt-creator,jonnor/qt-creator,syntheticpp/qt-creator,enricoros/k-qt-creator-inspector,AltarBeastiful/qt-creator,bakaiadam/collaborative_qt_creator,enricoros/k-qt-creator-inspector,darksylinc/qt-creator,KDE/android-qt-creator,dmik/qt-creator-os2,malikcjm/qtcreator,Distrotech/qtcreator,amyvmiwei/qt-creator,amyvmiwei/qt-creator,Distrotech/qtcreator,ostash/qt-creator-i18n-uk,xianian/qt-creator,Distrotech/qtcreator,omniacreator/qtcreator,syntheticpp/qt-creator,dmik/qt-creator-os2,yinyunqiao/qtcreator,maui-packages/qt-creator,Distrotech/qtcreator,darksylinc/qt-creator,duythanhphan/qt-creator,farseerri/git_code,enricoros/k-qt-creator-inspector,syntheticpp/qt-creator,AltarBeastiful/qt-creator,duythanhphan/qt-creator,danimo/qt-creator,kuba1/qtcreator,azat/qtcreator,amyvmiwei/qt-creator,martyone/sailfish-qtcreator,dmik/qt-creator-os2,amyvmiwei/qt-creator,maui-packages/qt-creator,colede/qtcreator,darksylinc/qt-creator,malikcjm/qtcreator,kuba1/qtcreator,martyone/sailfish-qtcreator,bakaiadam/collaborative_qt_creator,azat/qtcreator,renatofilho/QtCreator,duythanhphan/qt-creator,kuba1/qtcreator,ostash/qt-creator-i18n-uk,omniacreator/qtcreator,yinyunqiao/qtcreator,bakaiadam/collaborative_qt_creator,duythanhphan/qt-creator,jonnor/qt-creator,richardmg/qtcreator,malikcjm/qtcreator,yinyunqiao/qtcreator,martyone/sailfish-qtcreator,KDAB/KDAB-Creator,syntheticpp/qt-creator,martyone/sailfish-qtcreator,colede/qtcreator,dmik/qt-creator-os2,pcacjr/qt-creator,AltarBeastiful/qt-creator,ostash/qt-creator-i18n-uk,AltarBeastiful/qt-creator,enricoros/k-qt-creator-inspector,sandsmark/qtcreator-minimap,yinyunqiao/qtcreator,darksylinc/qt-creator,omniacreator/qtcreator,azat/qtcreator,farseerri/git_code,amyvmiwei/qt-creator,AltarBeastiful/qt-creator,KDAB/KDAB-Creator,amyvmiwei/qt-creator,danimo/qt-creator,sandsmark/qtcreator-minimap,Distrotech/qtcreator,kuba1/qtcreator,richardmg/qtcreator,ostash/qt-creator-i18n-uk,dmik/qt-creator-os2,hdweiss/qt-creator-visualizer,jonnor/qt-creator,farseerri/git_code,jonnor/qt-creator,maui-packages/qt-creator,yinyunqiao/qtcreator,sandsmark/qtcreator-minimap,darksylinc/qt-creator,bakaiadam/collaborative_qt_creator,KDE/android-qt-creator,maui-packages/qt-creator,danimo/qt-creator,malikcjm/qtcreator,xianian/qt-creator,syntheticpp/qt-creator,darksylinc/qt-creator,pcacjr/qt-creator,xianian/qt-creator,KDAB/KDAB-Creator,bakaiadam/collaborative_qt_creator,kuba1/qtcreator,pcacjr/qt-creator,renatofilho/QtCreator,enricoros/k-qt-creator-inspector,danimo/qt-creator,malikcjm/qtcreator,martyone/sailfish-qtcreator,sandsmark/qtcreator-minimap,azat/qtcreator,dmik/qt-creator-os2,duythanhphan/qt-creator,farseerri/git_code,dmik/qt-creator-os2,danimo/qt-creator,KDE/android-qt-creator,malikcjm/qtcreator,renatofilho/QtCreator,darksylinc/qt-creator,renatofilho/QtCreator,kuba1/qtcreator,hdweiss/qt-creator-visualizer,enricoros/k-qt-creator-inspector,richardmg/qtcreator,KDAB/KDAB-Creator,Distrotech/qtcreator,KDE/android-qt-creator,KDE/android-qt-creator,colede/qtcreator,KDE/android-qt-creator,renatofilho/QtCreator,KDE/android-qt-creator,pcacjr/qt-creator,ostash/qt-creator-i18n-uk,bakaiadam/collaborative_qt_creator,danimo/qt-creator,xianian/qt-creator,bakaiadam/collaborative_qt_creator,kuba1/qtcreator,maui-packages/qt-creator,richardmg/qtcreator,hdweiss/qt-creator-visualizer,maui-packages/qt-creator,malikcjm/qtcreator,renatofilho/QtCreator,yinyunqiao/qtcreator,danimo/qt-creator,maui-packages/qt-creator,danimo/qt-creator,omniacreator/qtcreator,KDAB/KDAB-Creator,colede/qtcreator,richardmg/qtcreator,KDAB/KDAB-Creator,pcacjr/qt-creator,enricoros/k-qt-creator-inspector,amyvmiwei/qt-creator,richardmg/qtcreator,farseerri/git_code,darksylinc/qt-creator,martyone/sailfish-qtcreator,sandsmark/qtcreator-minimap,danimo/qt-creator