BSC API updates

Hi all, I just pushed zecke/remove-use-count with two commits to almost complete the split. This code allocates the "struct gsm_subscriber_connection" dynamically and the follow on commit is removing the use_count and releases a channel as soon as it is unused (no operation/transaction is left on it). I would like to land this code now and continue with: -) Land some channel release changes from the On-Waves branch -) Update the channel release documentation... -) Start recreating the osmo-bsc... -) Implement the assignment command and use it from gsm_04_08.c and suddenly we can easily switch from very early to early assignment...