doc: fixes mostly around the occurences of &kde;

- the interface is not "&kde; integrated" (KDE is not the desktop,
  and labplot is a generic Qt/Frameworks applications anyway);
- similarly, use "KDE Frameworks" instead of "KDE" when needed;
- remove the not needed dash in "KDE Applications"';
- update the list of command line options: remove outdated options
  and add the new one;
- remove the useless &kappdata; entity.