Multiple Radios per node

[wizard97]

I think a relatively simple, and nice addition would be the ability for this library to handle multiple instances with multiple radios.

I think the changes would be relatively simple, currently there is just a public static RFM69 *self pointer, that gets called by the ISR. All you would have to do is create a simple linked list of RFM69 objects, add an additional attribute to the class that is a RFM69 *next pointer. Whenever the ISR fires, in the isr routine just traverse through the list and digitalRead each RFM69's isr pin to figure out which device triggered the interrupt, then call the associated handler.

[LowPowerLab]

Thanks for your thoughts, this was discussed before. In most cases there is 1 radio per module and I don't personally have a need for more. You're welcome to submit a PR if you'd like but any changes require extensive testing.