Running queries via dbus

[Jacopo De Simoi]

> 
> Ah, well the issue is that we're trying to pass back a float, but only doubles 
> are registered as valid D-Bus types by default.
> 
> In particular, Meta::Track has float as the return type of bpm().  Perhaps it 
> would be sensible to make this a qreal?  Also, score() should probably also 
> return qreal (rather than double) for consistency.

Probably qreal would be the better choice; would it be possible to change it only when using dbus, to minimize interference with other parts of the code? As far as I can tell this issue makes the dbus query interface basically useless in most cases. 

Thanks 

 __J