Implement wireless mesh

[kripton]

Currently, only "sniffer" and "broadcast" wireless modes are implemented. However, the RF24-library also supports a mesh mode (https://nrf24.github.io/RF24Mesh/index.html).This has the great benefit, that packets can hop from one node to another to extend the possible range. In the example topology (see https://nrf24.github.io/RF24Network/md_docs_tuning.html), let's assume the master node "00" is attached to a PC and receives DMX data from there. The nodes "015" and "025" are out of radio range of "00" and cannot directly receive the data. However, node "05" has "00", "015" and "025" in radio range and forwards data from "00" to "015" and "025".

However, the mesh is not "fully automatic" or self-healing. This means that some configuration needs to be done by the end user / operator.

Work in progress at main...kripton:mesh.

To clarify:

• How to implement "true broadcast" with RF24Mesh / RF24Network. "Multicast" between a group of nodes is implemented, but not a "broadcast to all nodes"
• How to keep stats / reachable nodes / mesh topology information available at every node?
• What about many nodes joining and leaving the network. Are the ids "burned" or can they be re-used?