Fix the ki18n usage issue and corrent the kmainwindow usage.
Fix the ki18n usage issue and corrent the kmainwindow usage.

pranavrc/example-gluon,KDE/gluon,KDE/gluon,KDE/gluon,pranavrc/example-gluon,KDE/gluon,pranavrc/example-gluon,pranavrc/example-gluon