Implemented IDO2DB socket buffer.

This should take care of the common problem where idomod is sending too
much data for IDO2DB to process right away which leads to idomod blocking
on a write() call for the IDO socket.
Use transactions for SQL queries (just for MySQL for now).

This experimental patch significantly increases IDO2DB's performance.
More testing is required to determine whether transactions are safe
for general use.
Merge branch 'gbeutner/idoqueue' into mfriedrich/ido
ido2db: add enable_socket_queue and add shroud's sauce opt-in

refs #3533
Merge branch 'mfriedrich/queue' into mfriedrich/ido

Conflicts:
	module/idoutils/config/ido2db.cfg-sample.in
	module/idoutils/src/db.c
	module/idoutils/src/ido2db.c
update Changelog and config updates for refs #3533
install: fix ido2db initscript uses same chkconfig line as icinga (Dirk Götz) fixes #3490
Merge branch 'test/ido' into next
import 1.6.2 1.7.4 1.8.4 Changelogs into upstream