Enhance checkConnection() function

[TMRh20]

• Define MESH_CONNECTION_CHECK_ATTEMPTS in RF24Mesh_config.h & add doc info

checkConnection() function:

• Return from checkConnection() if -2 received (not in list or default address)
• retry if -1 (write failed or timed out)
• success if address matches
• fail otherwise

This should enhance stability a bit by raising the connection check attempts to 3.

It should also enhance the actual connection check by returning immediately and not retrying if a -2 is received (not in list or default address).

Furthermore it actually verifies that the returned RF24Network address matches the existing RF24Network address.

[2bndy5]

cherry-picked to v1.x

[2bndy5]

Did you want to try that new bump-n-release workflow? Or do you have some more pleasant surprises in store?

[TMRh20]

I'm planning to do a little more coding over the next week or so, so lets see if I come up with anything else. This one I just came across while glancing at the code...