Translations break menu restructuring

[Alexander Dymo]

> Btw. the separators in the menu-bar should be "disabled". That makes
> them look more like separators (softer), and prevents a tiny menu from
> popping up when the mouse hovers them.
Done. 

I spend quite some time figuring out what would be the cleanest solution to 
have visible and disabled separators in the menubar.

When you write <Separator/> in the uirc, xmlgui correctly adds separators via 
QMenuBar::insertSeparator(), but that never gets shown (I suspect styles just 
don't do that).

It's also impossible to disable the "kdevseparator" actions via xmlgui states 
(as those menubar actions never get a KAction object).

So, I reimplemented KXMLGUIBuilder::createCustomElement in the mainwindow and 
made it possible to have visible and disabled actions for all <Separator/> 
tags. But, it turned out that uistandards.rc define one separator before Help!

I had to add an attribute to the separator to differentiate our separators 
from those from uistandards.rc: 
<Separator style="visible" />

If anyone can think of a better solution, please let me know. 
I'm interested :)