NRF24 Channel and Datarate in the MyTransportNRF24-constructor

[fleinze]

Hi,
I am missing the possibility to select a different channel without editing MyConfig.h. This comes in handy when I want to test some features in a test-system without impairing the main system.
In Library version 1.4 it was possible in the begin-statement of MySensors.h.
With the new architecture I think the MyTransportNRF24-constructor would be a good place for this. The new constructor would look like:

MyTransportNRF24(uint8_t ce, uint8_t cs, uint8_t paLevel, uint8_t channel, rf24_datarate_e datarate);

I made pull-request on github because I think this is a good idee.

[msamy.earth]

I need this feature. Where is your branch?

[hek]

It was merged a long time ago in the development branch.

Add
#define MY_RF24_CHANNEL 76

in sketch