As the common.h is only meant to be used by the network
shell files, rename it to be more descriptive in order to
avoid possible conflicts with any other common.h file.
Signed-off-by: Jukka Rissanen <jukka.rissanen@nordicsemi.no>
If user adds IPv6 address to the network interface, check
if the address is a multicast one and add it to multicast
group if it is.
Signed-off-by: Jukka Rissanen <jukka.rissanen@nordicsemi.no>