Add addressee to filtering system

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

New Ticket Notice

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

If an email arrives at the system and the system cannot determine why the
mail arrived (ie. a system email was not found in the To or Cc headers), the
recipients list should be maintained.

This is useful for generating collaborator lists as well as filtering by the
To and Cc (Addressee) headers.

pipe: For wrapped messages, use wrapped headers

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

07fec4c4 introduced the ability to receive
and process messages forwarded as a message/rfc822. However, the email
headers that were saved on file in the %email_info_table were the headers of
the outer message.

This patch pulls the headers from the wrapped message to be saved in the
database. This mainly addresses the email References and In-Reply-To headers
for the email responses from the system.

Send staff alerts as Notice as opposed to an AutoRely

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

Some emails providers (e.g gmail/google) won't deliver emails marked
bulk/autoreply to group email address.

Thread body revisited

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

This is required when validating a message which could be a string or an
object.

level.
Handle cases where thready body is sent in as a string

We're going to assume HTML of html thread is enabled - otherwise text is
assumed.

model.

This would in theory allow us to decide at the email level the content type
to accept.

Cleanup and make HTML safe by default
Strip empty lines in TEXT content

This will be helpful to keep track of whether a text is html or text and
provide a way to convert it exactly once.

Ensure images, when initially placed, have a width

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

html: PHP DomDocument classes are in the `dom` ext

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

Fixup Unicode whitespace mangling

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

Fix a few link issues in the ticket thread

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

Until we add text/plain bodies to the ticket thread without an enclosing
<pre> element, we should not treat the <pre> element like a code or
blockquote block.

On some combinations of operating systems, PHP and libpcre versions, `\s`
will match the iso-8859-x non-breaking-space, 0xa0. This regular expression
will munge the UTF8 encoded version, 0xc2a0 to 0xc220, which is not a valid
UTF8 character.

When inserted into a UTF8 field in mysql, the text will be truncated at and
after the first invalid character.

These functions don't appear to be used an could corrupt UTF-8 encoded text

Feature/auto replies

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