Some shortcut settings improvements

Don't display the useless "Other" category, since the categorization of
commands isn't used anywhere (candidate for removal).

Filter out accelerator ampersands, since they aren't interesting here
and reduce the effectiveness of searching.

src/plugins/coreplugin/actionmanager/actionmanager.cpp

@@ -222,7 +222,7 @@ ActionManagerPrivate::~ActionManagerPrivate()
     qDeleteAll(m_idContainerMap.values());
 }
 
-ActionManagerPrivate* ActionManagerPrivate::instance()
+ActionManagerPrivate *ActionManagerPrivate::instance()
 {
     return m_instance;
 }