This commit fixes a mistake where a variable was incorrectly set. This in turn fixes the lint tests.

- Clean up/correct notifyCollaborators function
- Make sure function calls are passing in all needed variables
- getContact function added to EmailRecipient class to properly set up email notifications
- Corrections on encoding recipients for thread entries

This commit addresses a few lint related issue - notable one is ignoring
undefined methods within source code comments.

Add support auto email-based auto-referral. This will happen if an email is
sent to multiple departments. For example an email with TO: support &  CC:
billing will result in the ticket getting routed to "support" department and
"billing" getting a referral of the same ticket. This allows both departments
to have visibility of the ticket - which is not possible at the moment.

This commit attempts to remove all coding standard warnings emitted by PHP
7.0.

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

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.

This correctly handles a bounce message with the following layout:

multipart/report; report-type=delivery-status
    multipart/alternative; differences=Content-Type
        text/plain; charset="us-ascii"
        text/html; charset="us-ascii"
    message/delivery-status
    message/rfc822

Here's an example email structure:
```
multipart/mixed
 - multipart/report; delivery-status
   - multipart/alternative
     - text/plain
     - text/html
   - message/delivery-status
   - message/rfc822
```

The previous code would only find the body if the email main headers had:
Content-Type: multipart/report; report-type="delivery-status". In such a
case it would scan for a plain/text body.

This patch will scan for the usual body if the scan for the body as usual if
the report scan did not find anything.

Also, output errors to stderr when running API from the command line

This also adjusts the logic internally to lookup the priority by the
priority_urgency field, which should be constrained to follow priority
precedence over the priority_id field.

Detach conversation thread from ticket to make it more generic. Any object
can now have its own thread complete with entry type and attachments.

This addresses cases where incoming emails doesn't include charset and
mailbox may include non-ascii characters.

function splitHeaders updated in order to correctly parse mail header lines
starting with tabs

Signals added:
  * mail.received
    Called after the mail is received into the system and before it is
    processed by the mail system. This signal is useful to do header
    injection. Raw message/rfc822 included in 'raw' key in the info

  * mail.decoded
    Called after the initial decoding of the message. The header and bodies
    are broken out, however, Unicode decoded may not have been performed
    yet. This signal is useful to affect the interpretation of the message,
    such as TNEF processing, etc.

  * mail.processed
    Called after all internal processing is completed. All Unicode
    processing is complete, bounce detection and other mechanisms have
    completed. This signal is useful to do things like attachment scanning
    or content filtering.

Otherwise, if a decoded email name has a comma in it, for instance

From: =?utf-8?B?RnJ5ZGVubHVuZCBIeW3DuGxsZXIsIEJldHRpbmE=?=
    <bettina.frydenlundhymoller@domain.com>

The address list will be parsed incorrectly since the comma has an ambiguous
significance. Usually, the personal name would be quoted; however, since it
is encoded, there is no need to quote it.

Sometimes an MTA may just send back the headers of the original message
rather than the entire original message. Such an email will have a
`text/rfc822-headers` part which will be the complete headers of the
original message.

Without this patch, osTicket will create a new ticket for the bounce message
rather than attaching the new internal note to the existing ticket.

References:
https://tools.ietf.org/html/rfc1892

Such images are attached to emails by Lotus Notes. Technically, these images
are valid attachments, although historically osTicket would reject them

email.

This is necessary to eliminate possible loop when an email is sent to a
virtual/aliased address. Not all mail servers add delivered-to header!

If a non-text attachment specifies a charset in the content-type header,
don't transcode the content before saving it to the database. This can
corrupt attachments which have a header like the following:

Content-Type: application/pdf; charset=UTF-8

Since a PDF contains binary data, coercing it to UTF-8 encoding will drop
characters not valid in UTF-8 and will corrupt the attachment data.