Include collaborator tickets on search by user.

search: Improve typeahead search results

Reviewed-By: Peter Rotich <peter@osticket.com>

Fixup search for users with hits in an searchable authentication backend:

  * If there is a hit for the remote backend, include that in the search for
    local users by email address. If there is a hit locally for the same
    email address, then remove the remote hit from the search results.

Fixup typeahead results

  * Abort previous search requests when the user enters more text into the
    search fields. This makes the search box feel more consistent, and
    avoids the case where the user finishes typing and valid search hits
    never appear

Pluggable storage infrastructure

Reviewed-By: Peter Rotich <peter@osticket.com>

If a plugin refuses to be uninstalled, allow it to set an error to be
displayed on the management page.

Add `attrs` field for backend state information (multi-part migration,
multi-part upload, etc). Change `size` to be an integer rather than text
field. (Storage space will be about the same, but int makes more sense).
Size the `key` and `signature` for ~512 bits. The base64 encoding allows
6-bits per char. At 86 chars, we have 516 bits maximum space.

Fixes the rewriting of the `key` field in the ticket thread body. The
storage de-duplication system may replace the `key` value with an existing
one. The ticket thread system will use the `key` value assigned when the
file is committed to the database or the existing key of the duplicate file.

Also fixup installation issues with the attachment storage plugin
architecture

  * Include a `bk` column to store the storage backend
  * Include a `signature` column which represents a repeatable hash of the
    file contents
  * Rename `hash` to `key` since it isn't a real hash

Authentication backends revisited

Sorta-Reviewed-By: Jared Hancock <jared@osticket.com>

This allows SSO backends to ingore authenticate method

No need to execute signal connect for each request!

SSO was originally used for a SSO plugin. The backend has since been
refactored to support other authentication backends.

Reafactor logOut to use the piggyback on auth backend

The concept of extid is being retired to pave-way for customizatable ticket
numbers.

 - This is necessary so we'll have a name on record - even on user deletion.

Pass the user id (uid) to ticket create instead of unpacked data.

Make sure new message notice goes to the user who posted the message not
neccessarily the ticket owner.

Using email headers try to determine the user.

With the introduction of collaborators, this is necessary so we can determine who is replying without relying on the
FROM address - which can be easily spoofed.

Conflicts:
	include/class.cron.php

If the entry answer being updated does not affect the ticket details form
(with type=T), then the updates do not need to be applied to the
ticket__cdata table.

Several database performance tweaks

Reviewed-By: Peter Rotich <peter@osticket.com>

This is instead of optimizing the lock table for every cron run, which
wastes a lot of db server io