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/git/gitversioncontrol.h

@@ -44,7 +44,7 @@ class GitVersionControl : public Core::IVersionControl
 public:
     explicit GitVersionControl(GitClient *plugin);
 
-    virtual QString name() const;
+    virtual QString displayName() const;
 
     bool managesDirectory(const QString &directory) const;
     virtual QString findTopLevelForDirectory(const QString &directory) const;