one of the benefits of plasma getting bug reports for _everything_ is i end up seeing things that bug me while triaging them ... e.g. the config dialog of kmenuedit. so:

* Misc -> General (i18n'd elsewhere in kmenuedit already, so no string breakage)
* give it an icon
* move it above spell check config as per most KDE apps
* add a spacer to the bottom of the layout so the UI is at the top, not floating in the middle vertically
* get rid of the superfluous groupbox