Make IDocument::fileName a member with setter.

Instead of requiring subclasses to implement a method.
Also renames IDocument::rename to IDocument::setFileName,
since it doesn't really rename any files or such.

Change-Id: I1344025c24d2f74a6a983e04fb0a5245f1f37aad
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/diffeditor/diffeditorfile.h

@@ -48,7 +48,6 @@ public:
     explicit DiffEditorFile(const QString &mimeType,
                               QObject *parent = 0);
 
-    QString fileName() const { return m_fileName; }
     QString defaultPath() const { return QString(); }
     QString suggestedFileName() const { return QString(); }
 
@@ -58,9 +57,7 @@ public:
     bool save(QString *errorString, const QString &fileName, bool autoSave);
     ReloadBehavior reloadBehavior(ChangeTrigger state, ChangeType type) const;
     bool reload(QString *errorString, ReloadFlag flag, ChangeType type);
-    void rename(const QString &newName);
 
-    void setFileName(const QString &name);
     void setModified(bool modified = true);
 
 signals:
@@ -69,7 +66,6 @@ signals:
 private:
     const QString m_mimeType;
     bool m_modified;
-    QString m_fileName;
 };
 
 } // namespace Internal