since a subscriber is an element of the gsm_network, we have to ensure
subscr->net is always set correctly. We do this by using gsm_network
as an argument to all functions that resolve or create a subscriber.
For further evaluation/analysis, this patch stores the classmark 1, 2 and 3
values of every equipment in the SQL database. We can use this non-volatile
data to determine the supported features for each handset that we've ever
seen on our network.
* describe data structures in gsm_04_11.h
* increae LCHAN RELEASE TIMEOUT for case of long SMS
* convert header field in sql table from NUMERIC to BLOB
* initial handling for validity period
* send RP ERROR messages with meaningful RP CAUSE in case of error