issue: Mbstring Extension Requirement

This addresses an issue reported on the forum where printing a ticket in
v1.12 and above requires `mbstring`. This updates the print call to check
for the `mbstring` extension and if not loaded will fail with a detailed
error `mbstring extension required to print ticket to PDF`.

Instantiate  StaffDeptAccess

Datetime Formats

This commit addresses two issues related to date / time format.

* 24 hrs format, when selected, is now used system-wide even on thread items
* PHP-to-JS date / time format translation is now down in the backend

issue: Revert 453e8152

issue: Complete Thread Var Padding (Outlook)

This addresses issue 5007 where when using the complete thread variable
there is no padding between thread messages in Outlook desktop app and makes
the thread hard to follow. Outlook does not respect some CSS rules that are
accepted in most (if not all) modern email clients. Since we can’t use
normal CSS the workaround is to add a blank table row (with a single space)
so that it forces "padding" between the end of a message and the start of
another.

Before
(image)

After
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This addresses an issue where upgrading from v1.6 to a release on or after
v1.12 will hang on login and eventually timeout. This is due to the system
not being able to fetch the config which logs a db error which calls the
config and continues the loop. For now, we need the config in the
constructor so that the loop doesn't occur and we can continue to upgrade as
normal.

TODO:
- For a permanent fix, we need to figure out why the loop occurs when not in
the constructor and vice versa.

issue: PHP 7.3 New Agent Set Password

Issue: Empty Due Date

This commit fixes an issue that allowed Agents to clear the Duedate on a ticket using inline edit. We were saving the value 0000-00-00 00:00:00 to the database which the ticket would then display as 12/1/02 06:09 pm.

Instead, if an Agent clears the Duedate field, we should save the duedate as null and the ticket should continue using the est_duedate.

This addresses an issue reported on the Forum where creating a new Agent and
setting a password hangs when using PHP 7.3. This is due to too few
arguments passed to `PasswordPolicy::checkPassword()`. This updates the call
to include a second argument of `null` so the method is satisfied and we can
continue with checking the password.

Revert "issue: Advanced Search Default Sorting"

This partially reverts commit dda483eb.
Forcing created by sort resulted in queue columns based sorting getting
overridden.

European Date Format Issue

This commit fixes an issue where if your date format is dd/MM/y h:mm a, the date picker will show the wrong year because the dates were not translating correctly between PHP and JS.

Issue: Annul Closed Events

issue: CSV Patch Adv. Search Error

This addresses an issue where the previous CSV security patch causes an
error when creating an Advanced Search with criteria like `User / Email
Address => contains => @domain.tld`. The system tries to validate the field
and since `is_formula` is the default validation for TextboxFields the
system sees `@domain.tld` criteria as a formula and throws the `Content
cannot start with the following characters: = - + @` error. Advanced
Searches do not need the `is_forumal` validation as the fields are not
exportable. This adds a check to see if the field's form is
`AdvancedSearchForm` and if there is no `validator` set it gets set to `adv`
which bypasses the validation.

This commit fixes an issue where if you were to change a Ticket to the Resolved status and then to Closed, the dashboard statistics would show that you had closed 2 Tickets even though both events were done on the same Ticket.

We should only count one closed event per Ticket.

This was reported in Issue #5018.

Required Short Answer Field = '0'

Date Range Period  / User's Timezone

issue: Department Referral Email

This addresses an issue where a User sending an email message with a
different Department as CC to the system will not refer the CC'ed Department
until the email is fetched a second time. The old thinking was that since
the User CC'ed the other Department the other Department should receive a
copy of the email in their mailbox. When the system fetches the User's
message from the original Department email it gets added to the thread but
doesn't refer just yet. When the system fetches the copy of the message from
the User in the other Department's email it will then refer the other
Department. This is a problem especially when you are not fetching or
forwarding from the other Department's email address. This updates
`Thread::postEmail()` to include the check for `$mailinfo['system_emails']`
and if set we refer the Department immediately.

This commit fixes an issue where date range boundaries didn't consider
user's timezone resulting in UTC times being used.

Issue/ticket preview collabs

i18n: Register Include

This addresses issue 4965 where the register.inc.php file for clients was
missing translations for the action buttons.

issue: Set Staff Password On Creation

Update osTicket Requirements

- PHP 7.0-7.3
- MySQL 5.5

feature: Expanded Print View

issue: Dashboard No Help Topics Error

Update osTicket Requirements