upgrader: Fix upgrade from osTicket 1.6

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

This happens when upgrading from 1.6, the company information does not yet
exist (neither do the form tables)

Properly escape company name for display

oops: Don't crash on setting Return-Path

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

file: Use the database to save files as a failsafe

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

file: Fix saving backend char

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

Fix export of custom list fields

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

oops: Fix display of forgot-my-password link

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

Use the company name on the copyright notice.

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

Use up-to-date user/staff name instead of poster when displaying ticket thread

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

Join to staff/user tables to get current name when fetching thread entries.

Reported by @ntozier

Expose staff's signature as a variable in collaborator's template

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

Only add emailed collaborators if we have a positive match

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

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!

Because the file type normally defaults to the system default (for fetched
emails at least), the backend char was not saved, because the file type char
was left at the system default. Therefore, if a file is saved to a backend
other than the default (in the database), the data will likely be saved to
the backend, but the file metadata will reflect the incorrect backend.

The only reason the file type char was not defaulted in the
AttachmentFile::save() method was for the migration process from osTicet 1.6
to osTicket 1.7. This is mitigated by passing `false` specifically from the
migration task.

Since otherwise the file type char is now set, the backend char is now saved
with the file metadata.

Correctly process email tickets for existing users

Reviewed-By: @rougeAU
Reviewed-By: @syscom2
Reviewed-By: @centoasa
Reviewed-By: @vhadjisophocle

If a ticket is created via email for an existing user, under some
circumstances, no user will be associated with the new ticket.

If a remote user is found by name and does not have an email address, a bad
SQL query would be generated

Conflicts:
	setup/test/tests/stubs.php

Careful transcoding attachments with a charset

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

tnef: Strip null bytes from attachment filenames

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

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.

Also support the TransportName in the properties list and prefer it over the
attachment-level attribute, as it is Unicode encoded.