Lay down current namespace practices

Change-Id: I16e6e292097f3f7289bda8d9c6c23b6827ee54b9
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>