Zabbix

...G...... [DEV-1353] fixed watch package subsription handling, simplified required interfaces

* commit '9083e515832a5c96fd571e094a12bd2414a84284':
  ...G...... [DEV-1353] disabled debug plugin, fixed default active checks file location
  ...G...... [DEV-1353] fixed watch package Flush() method
  ...G...... [DEV-1353] removed redundant code
  ...G...... [DEV-1353] moved output flushing to separate function so watcher could send bulk notifications without flushing output after each notification
  ...G...... [DEV-1353] updated prototype debug.filewatcher plugin to work with latest watch package changes
  ...G...... [DEV-1353] added event source initialization error caching
  ...G...... [DEV-1353] refactored watch package, added comments, removed redundant functionality
  ...G...... [DEV-1353] fixed item filter subsription removal

(cherry picked from commit 802c0e952ec2474df40a7dae62d910d645658b2c)