Change z-index to overlay popup windows correctly

Show ticket prview when a ticket number is clicked as opposed to ticket
view.
Add collaborator preview tab on ticket preview tool tip.

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>

Fixes a few E_NOTICE messages
Drops bounce checking inside autoReply checking

mysqli: Retry on deadlock-found error

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

oops: Fix finding key of existing file

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

If MySQL error #1213 (deadlock found when trying to get lock) is returned
from query, it is safe to retry the query.

This patch will retry queries up to two times for a total of three. If the
query cannot be executed without error #1213 after the third time, the error
is logged as usual, and the system continues with the failed query.