enforce stream correlation against same-numbered old streams

fixes port mixups in case of one rejected stream (zero port) when
using UDP protocol
merge bencode fix from kamailio source
change port range defaults to match docs
MT#4569 ngcp-mediaproxy-ng-daemon does not need to Pre-Depend on ngcp-mediaproxy-ng-kernel-dkms

As reported at https://github.com/sipwise/mediaproxy-ng/issues/9

Closes: #9
Thanks: Peter Dunkley for reporting
Merge branch 'master' of git.mgm.sipwise.com:mediaproxy-ng
Implement non-fatal warnings in NG replies and use them in "delete"

Closes: #12
2.3.1
(cherry picked from commit 06a352d6556df6bdd7ba061e00272f86b4eb6364)
update changelog to 2.3.2
remove potentially unnecessary include
add GPL3 license text and update outdated debian/copyright
fix incorrect backward behaviour regarding the "c" flag

fixes #15
fix possible segfault on incorrect sp/SP flag usage