[vdr] force cDevice::GetDevice

[Markus Hahn]

Hi there, 
I am going to enhance Channelscan-Plugin for DVB-T and DVB-C. 

The scanning will be implemented as "blind scan", and it should 
work with different hardware sets. eg. two DVB-S and one DVB-T tuner 
or two DVB-C tuner. In other words I need  a reliable way to get a device.
Actualy I use this for the moment (DVB-S only, valid transponders only) :

...  if (cDevice::GetDevice(i)->ProvidesSource(sourceCode)
      & !cDevice::GetDevice(i)->Receiving(true))

       SetTransponderData(... 
       cDevice::GetDevice(i)->SwitchChannel( ...  

if that fails (no lock), I go further 

if (cDevice::GetDevice(i)->ProvidesSource(sourceCode)
                && cDevice::GetDevice(i)->Receiving(true)
                && !cDevice::GetDevice(i)->Receiving())
           {

      SetTransponderData(... 
       SwitchChannel( ...  

But this solution is to weak. Actual, sometimes I don`t get a vaild device at 
all with  valid transponders.

Of course recordings or live view could be shutting down if needed. 

Any suggestions? 

Regards Markus