Qt4ProjectManager: Rename {Qt4,Qmake}{Project,Pr{i,o}FileNode}

Change-Id: I27139d8ccc17b665853bec4a37e80568680b5fcc
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
Reviewed-by: David Schulz <david.schulz@digia.com>