dynamicaly check if radius module loaded (so not more require to rebuild project without RADIUS to switch to chap-secrets)

radius: additional statistics

radius: fixed bug of double packet free when second DM request received in time when radius sends Accounting-Request Stop

radius: implemented accounting interim update timeout

radius: implemented acct-interim-interval option to specify interval to send accounting information if radius Acct-Interim-Interval attribute is absent in Access-Accept

radius: introduced dae-server option to configure Dynamic Authorization Extenstion (DM/CoA) instead of dm_coa_secret

radius: send Acct-Session-Id in Access-Request packet if sid_in_auth option is set (for broken billings)

radius: bind parameter to bind to ip other then nas-ip-address

radius: accounting start moved to before ip up

radius: implemented extension Acct-Input-Gigawords, Acct-Output-Gigawords
lcp:    implemented maximum/minimum mtu/mru checks

        and newly introduced -  ip-change, when radius CoA request received,
        also this module manages pppd compatible radattr.pppX files
core:   implemented module 'sigchld' which handles SIGCHLD signal,
        waits child processes to terminate and manages pid terminate handlers