Fix case where collaborators were not being alerted
Alert admin last on new ticket - just in case admin email is used by an agent.

This patch changes the way the thread entry type and other properties are
determined by using the userClass determined in the Mailer::decodeMessageId
method which is preferred over the older heuristic methodology using the
`From` email address alone.

Only send one autoresponse to the same user for new messages sent in a five
minute window per thread. This will stop looping because of bounces and OoO
notifications not flagged as autoreplies

Redirect to recent queue / listing on transfer or assign

And two flags, one which signals that stored HTML is correctly balanced and
does not need to be balanced when rendered in the ticket view. The second is
used to signal messages received from collaborators.

Additionally, this patch fixes showing external inline images (via the [Show
Images] button) when clicked.

Initially, include support only for Gravatar

getVar() is now called first, then object properties and array properties
are considered, and then getTag() is considered if none of the other options
work. This allows for more predictable results using the variable
replacement system, and allows ::getVar() to override every other means to
use variables in email templates.

This adds the concept of independent multi-thread rendering

Thanks, @torohill

Ensure that for entries having the same create timestamp, the ID sequence
number is used so that entries inserted first are rendered first in the
thread.

* Log events for AJAX collaborator list edits
* Avoid extra selects for inline image handling
* Avoid using htmLawed to add target="_blank" and class="no-pjax" to links
  in the ticket thread
* Cache instances of IntlDateFormatter; seems expensive to set up
* Cache filetypes Yaml in APC if available
* Cache I18n::getDefaltLanguage() in the request
* Avoid extraneous usage of Model::_inspect and Model::$meta
* Add aggregated query support to the ORM
* Lazily compile SQL query for InstrumentedLists
* Apply `select_related` setting when setting up InstrumentedList instances
* Slight optimization in SqlCompiler::getField
* Avoid double compiling Sql annotations in the ORDER BY clause
* Cache Thread::getEntries
* Break out event types for ThreadEvent for more legible code
* Eliminate one query from Ticket::loadDynamicData
* Fix ticket number bolding if already answered
* Use dependent subqueries for ticket statistics in the queue page, which is
  significantly faster for large data sets (like hundreds of attachments or
  thread entries)
* Fixup sidebar layout on client knowledge base pages

* Fix crash in Ticket::getLastRespondent
* Fix crash is ORM if using a superclass of a relationship from cache. For
  instance, if the cache contains an ObjectThread instance, but a
  TicketThread instance is required in the relationship. In such a case, use
  the cached data, but change this class. This; however, violates the single
  nature of cache entries.
* Fix spurious events appearing after upgrade due to deleted tickets
* Ensure floating content in thread-body divs does not float past the bottom
* Provide an anchor to thread entries
* Show thread entries before events where both have the same timestamp
* Fix double events for collaborator additions
* Credit email sender with collaborator addition
* Fix incorrect rendering of collaborator addition event
* Fix crash on new ticket due to non-static function
* Fix missing sort on sub-query if explicitly declared in QuerySet
* Fix missing parentheses in SQL for ['field__eq' => QuerySet]
* Fix incorrect SQL on compileSelect for models with inherited $meta['table']
* Dynamically adjust relative time client side

And also fix mishap events changing the ticket status

This patch (which needs further development), introduces an extra field to
the %attachment table to store a file's name, in the event that two files
with the same content are stored in the database with differing names. In
such a case, the name is stored in the %attachment table. This allows the
attachment to specify a different name each time the same file is attached
to something in the system.

* Reindexing did not properly flush the last batch of items to the search
  therefore reindexing would always miss the last few items.
* Creating a new html thread entry with inline images resulted in empty
  search content
* HTML tag stripping in HtmlThreadBody::getSearchable() would result in
  missing white space between some words, resulting in poor searchable
  content

The setting is no longer ticket thread specific. Disabling html is now
system wide setting for disable-able textarea widgets as well as email
correspondence.

Also log client edits as an event

This patch removes several of the internal notes posted to a ticket for
various events and replaces them with events added to a threads event chain.
The emails are still sent out as they previously were, but internal notes
are only added to the thread if an agent actually specified comments.

Move collaboration implementation to thread level

This will allow for any threadable object to render the thread.