Zabbix

A.F.I...S. [ZBXNEXT-250] added support of global and per-user time zones for frontend, notifications and for time limit when notifications are sent

* commit '6ab6d624b7051c6f69f91afa1406f7f431ac661e': (37 commits)
  .D........ [ZBXNEXT-250] fixed ChangeLog entry
  .D........ [ZBXNEXT-250] added ChangeLog entry
  .......... [ZBXNEXT-250] fix after review
  .......... [ZBXNEXT-250] fix after review
  .......... [ZBXNEXT-250] comments added
  .......... [ZBXNEXT-250] comments added
  .......... [ZBXNEXT-250] fix after review
  .......... [ZBXNEXT-250] test added to SeleniumTests
  .......... [ZBXNEXT-250] new autotest testTimezone added, minor changes in data_test.sql, testLanguage short fix
  .......... [ZBXNEXT-250] new autotest testTimezone added, minor changes in data_test.sql, testLanguage short fix
  .......... [ZBXNEXT-250] new autotest testTimezone added, minor changes in data_test.sql
  ..F....... [ZBXNEXT-250] fixed user time zone and theme not being taken into account in the setup wizard
  A.F.I...S. [ZBXNEXT-250] changed the default time zone from "UTC" to "system"; added ZBX_NODATA flag to users.theme
  ........S. [ZBXNEXT-250] changed default system time zone to be have value "system" instead of being empty
  ..F....... [ZBXNEXT-250] fixed undefined index error if guest user is enabled
  ....I..... [ZBXNEXT-250] reverted unnecessary changes
  A.F.I..... [ZBXNEXT-250] added ability to configure time zone
  ........S. [ZBXNEXT-250] coding style fix
  ........S. [ZBXNEXT-250] style fix
  ........S. [ZBXNEXT-250] added function header
  ...