[Development] Namespace macros for Qt Add-Ons

[henry.haverinen at nokia.com]

Hi Lars,

We've previously recommended that add-on modules should wrap their public
interface in C++ namespaces like QtBluetooth, QtOrganizer, QtJsonDb and so
on. 

Should there be some guidance for the namespace macros? Especially the
macros for using the namespace, which are used in application code. I
assume they are introduced to prepare for the possibility of moving the
module to Qt Essentials and removing the namespace.

Now we have macros like:

QTORGANIZER_USE_NAMESPACE
QTBLUETOOTH_USE_NAMESPACE
Q_USE_JSONDB_NAMESPACE

So it's not consistent at the moment, which makes the macros
non-guessable. What would be the right thing to do here?

Cheers,
Henry