configure.in: enable silet rules by default

Makes the compilation output more graspable.

Signed-off-by: Balazs Scheidler <bazsi@balabit.hu>
configure.ac: rename from configure.in

The configure script has a preferred extension of .ac, so rename it to
adjust with times.

Signed-off-by: Balazs Scheidler <bazsi@balabit.hu>
stomp: Added initial stomp destination support.

Patch based on Nagy, Attila <bra@fsn.hu> patchset, but using our own
stomp implementation, instead of libstomp to avoid APR as dependency.
Merge branch 'merge-queue/3.5' of https://github.com/talien/syslog-ng into feature/stomp-destination
stomp: Finished stomp destination.

Added ERROR checking, and RECEIPT (ack) support.
Added tests for STOMP proto parsing.
At ERROR frame receiving, we should drop the connection.