Make method naming more consistent.

* Use id() for methods returning a string used to represent
    some type of object.
  * Use displayName() for strings that are meant to be user
    visible.
  * Quieten some warnings while touching the files anyway.
  * Move Factories to their products in the plugins where that
    was not done before.

Reviewed-by: dt

src/plugins/cpptools/cppfilesettingspage.h

@@ -98,9 +98,9 @@ public:
     virtual ~CppFileSettingsPage();
 
     virtual QString id() const;
-    virtual QString trName() const;
+    virtual QString displayName() const;
     virtual QString category() const;
-    virtual QString trCategory() const;
+    virtual QString displayCategory() const;
 
     virtual QWidget *createPage(QWidget *parent);
     virtual void apply();