Fix for Multicast to level 4

[TMRh20]

#226

• Define NETWORK_MULTICAST_ADDRESS_LEVEL_2 and NETWORK_MULTICAST_ADDRESS_LEVEL_4 in RF24Network.cpp
• Add the above to valid addresses in is_valid_address();

[2bndy5]

Does net level 3 not have any problems? Or are we only compensating for known/reported problems?

[TMRh20]

Hmm, this library IS a bit confusing. Level 3 is 0100 or the default NETWORK_MULTICAST_ADDRESS, so it is accounted for. The only thing I'm curious about is potential conflicts between multicast address level 1 (01) and assigned address at RF24Network address 01 as they are the same digit... I haven't had a chance to look into it at all.

[2bndy5]

Oh right. I was confusing 04444 with NETWORK_MULTICAST_ADDRESS. Obviously, its been a while since I actually looked at the code in depth.

As for the 01 conflict, we could use a reserved bit in the header to distinguish between multicast or direct writes.

[TMRh20]

As for the 01 conflict, we could use a reserved bit in the header to distinguish between multicast or direct writes.

Is it needed? I don't quite know yet. I also thought about just changing the multicast level addresses to 06... or 07, 070, 0700, 07000