Allow edit *.ui files.

I have lots of self-made plugins. All my applications are built as simple "loader" and large plugins set. While working with plugins in QtCreator I have often restart it. Plugins cannot be reloaded by QtDesigner. This requires restart QtCreator each time when slots or signals in plugin are added, changed or removed. Then I must reconnect all changed signals/slots again. This all is VERY ANNOYING. Unfortunately direct editing is prohibited in .ui file text view. Therefore in QtCreator I have added Kate as extra editor for .ui files. Successfully I find changed signals and slots and change them. Often I even add new signal or slots in text editor. Then I save and close this file. Designer reopens it to just check connections. Now I request for allowed direct .ui text editing in Designer. This can be even protected by Designer setting.