Zabbix

.......PS. [DEV-3775] added database connection pool

* commit '9b06790710552acca03f39ccfcf7d2279bd99081': (23 commits)
  .......PS. [DEV-3775] improved/fixed comments
  .......PS. [DEV-3775] fixed comment and style issues
  .......PS. [DEV-3775] fixed comments
  .......PS. [DEV-3775] added comments
  .......PS. [DEV-3775] added exit on failure to lock/unlock database pool mutex
  .......PS. [DEV-3775] added comments
  ..F....... [DEV-3775] added item key zabbix[db,pool] to item key select
  .......PS. [DEV-3775] fixed dbpool limit setting error messages
  .......PS. [DEV-3775] added limits to dbpool max open/idle settings
  .......PS. [DEV-3775] fixed includes
  .......PS. [DEV-3775] fixed typo
  .......PS. [DEV-3775] fixed dbpool_set_idle_timeout validation error message
  .......PS. [DEV-3775] improved dbpool rtc error messages
  .......PS. [DEV-3775] fixed rtc dbpool_status option parsing
  .......PS. [DEV-3775] fixed indentation of dbpool info messages
  .......PS. [DEV-3775] updated diaginfo locks section
  .......PS. [DEV-3775] fixed indentation
  .......PS. [DEV-3775] renamed total connection limit from max_conn to max_open
  .......PS. [DEV-3775] updated database connection pool default settings
  .......PS. [DEV-3775] updated help messages
  ...