Zabbix

A.F.I...S. [ZBXNEXT-1150] added storage and display of event suppresions/unsuppresions due to maintenance

* commit '2da64386d712bdf4f3c1e59b17797643aca17cb8': (31 commits)
  ..F....... [DEV-4726] minor code refactoring and coding style fix
  .......... [ZBXNEXT-1150] corrected spelling error
  ..F....... [DEV-4726] fixing problem view CSV data to show user actions related to event suppression
  ..F....... [DEV-4726] fixed csv export to display correct suppressed by information
  .......... [ZBXNEXT-1150] added comments
  ..F....... [DEV-4726] changed class to attribute for icons in tables and list forms
  .......... [ZBXNEXT-1150] Selenium: changed the unsuppressed label in testFormUpdateProblem_CheckSuppressIcon
  ..F....... [DEV-4726] added back the "title" attribute for icons
  ........S. [ZBXNEXT-1150] removed foreign key from event_suppress.maintenanceid
  A......... [DEV-4726] removed changes in Maintenance API
  ..F....... [DEV-4726] Fixed inconsistent action names in CSV
  ..F....... [DEV-4726] added screen reader support for event suppression/unsuppression icons
  .......... [ZBXNEXT-1150] fixed style issue
  ........S. [ZBXNEXT-1150] fixed spelling and style issues
  A......... [DEV-4726] renamed method "addMaintenanceUnsuppressionRecords" => "createUnsuppressionAcknowledgements"
  A......... [DEV-4726] code refactoring
  ........S. [ZBXNEXT-1150] reverted part of overlapping maintenance period handling changes
  ........S. [ZBXNEXT-1150] fixed handling of maintenance updates and improved handling of overlapping periods
  ........S. [ZBXNEXT-1150] removed unnecessary DB changes
  A......... [ZBXNEXT-1150] moved the call of the system function time() out of the loop
  ...