[HELPER] count_cs

Signed-off-by: etienne <etienne.basset@ensta.org>
[MEDIUM] count number of conversion specifier in expr; rename match_expr_simple => single

Signed-off-by: etienne <etienne.basset@ensta.org>
[MEDIUM] if there was CS in expr but we didnt find any, consume anyway from ap_list

Signed-off-by: etienne <etienne.basset@ensta.org>
[DOC] document struct known_subnets

Signed-off-by: etienne <etienne.basset@ensta.org>
[MINOR] add DDN decoding off subnet mask for IPv4

Signed-off-by: etienne <etienne.basset@ensta.org>
[REGTEST] output info of ipinfo has changed

Signed-off-by: etienne <etienne.basset@ensta.org>