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/mercurial/mercurialcontrol.h

@@ -49,7 +49,7 @@ class MercurialControl: public Core::IVersionControl
 public:
     explicit MercurialControl(MercurialClient *mercurialClient);
 
-    QString name() const;
+    QString displayName() const;
     bool managesDirectory(const QString &filename) const;
     QString findTopLevelForDirectory(const QString &directory) const;
     bool supportsOperation(Operation operation) const;