Settings for storage backend and general max size setting for agents

Add initial concept of activity alert/subscription model to ticket activity.

This patch converts the central file and threading classes over to use the
ORM.

This patch removes the selection of canned responses as well as the canned
responses navigation page from the ui when the canned responses feature is
disabled.

Introduce the concept of tasks. Tasks are to do list that can be attached to
any object e.g Ticket.

Allow fields to be configured for view / edit / required for both agents and
end users. Fields can also be disabled now so that the field remains in the
form but is no longer displayed for new entries.

Allow tickets to be created without a subject — use the help topic full name
instead.

Also fix syntax error preventing deletes and drop the [manage all phrases]
feature for now.

This patch adds support for automatic date and time formatting based on a
selection of locale. The locale can default to the system or user specified
language+locale, or can be elected separately. For instance, English
speakers can pick between US, GB, and many other English speaking locales.

This also removes the need of the %timezone table and uses the timezonedb
built into PHP 5.3+. User's can now select from a much longer list of
database and no longer need to deal with the DST checkbox.

to indicate the primary language expected for translatable content

Determine and set a reasonable max file size on install
Remove file extension restrictions - transition to mime types

And fixup the migration patch

Help topics and filters can override the default status

Ticket numbers are now configurable as a system-default and by help topic.
Previously, an administrator could select between six-digit random and
sequential numbers. Now, the sequence is selectable so multiple sequences
as needed, and a format can be specified to define how the ticket numbers
look. Formats can also be defined for each help topic.

Multilanguage Support via gettext

- added gettext encapsulations to all texts i thought necessary
- added fallback function for the case that the gettext extension isn't loaded
- added browser language detection
- added gettext to the list of optional extensions in setup
- rewritten some of the texts to use sprintf instead of appending strings
- added german translation file
- removed mark_overdue-confirm from cannedresponses.inc.php

extend multi language support and a fex fixes

- Better detection of translation files
- Added functionality to redirect language codes (see redirecting
language codes)
- Ticket Status can be translated
- The Datepicker can be translated
- Extended functionality of 'testlang.php' to show what language code is
used to translate

Forgotten to apply a patch from RC5 to RC6

- Forgotten to change $var to $vars in line 380 of class.mailfetch.php
- Removed unneeded comment

Added php_gettext as primary translation engine

- Added php_gettext support (thanks to Danilo Segan and Steven
Armstrong)
- php_gettext is now the primary translation engine
- Extended language detection functionality

Add error/misconfiguration checks and fix undefined variables

Starting with osTicket 1.8.1, users must receive an email and follow a link
in the email to get access to the ticket. With this new option, the email
verification step can be avoided in osTicket 1.9, because access is now only
granted to exactly one ticket.

Use the topic associated with the email if any, and the topic defined as the
system default as the last resort. In either case, the form associated with
the help topic will be added to the ticket, but no data will be put into the
form fields.

Add ability to disable canned responses
Fix team drop down selection
Remove priority escalation setting in SLA page (implementation is on todo
        list)