Rename IDocument::fileName --> filePath

That is what it actually is, wrt how Qt API calls it.

Change-Id: Ied02055debf6aad75556b0d9d22e8ba2f72be555
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/genericprojectmanager/genericproject.cpp

@@ -457,7 +457,7 @@ GenericProjectFile::GenericProjectFile(GenericProject *parent, QString fileName,
       m_project(parent),
       m_options(options)
 {
-    setFileName(fileName);
+    setFilePath(fileName);
 }
 
 bool GenericProjectFile::save(QString *, const QString &, bool)