Fixes #198

Previously, html-like content would have to be run through Format::htmlchars
before being passed to Format::sanitize, because things that looked like
invalid html content would be removed.

A mail client may indicate a header parameter (such as Novell Groupwise,
which may add something like

Content-Disposition: inline; modification-time: "Thu ..."

) Previously, the system would not consider the content to be a candidate
for the email body, because it has parameters to the content-disposition
header.

This patch will still consider the part to be a candidate for the body if
the mime types match and no filename is found in the content-disposition
parameters.

Fixes #191

There's a unique index on %user_email.address, so there's no need to create
an index on %ticket.email when matching up records.

And avoid double encoding email bodies if html thread is not enabled

Handle cases where email headers contain unicode or high-ascii characters
and are not encoded according to RFC-2047. This patch handles a special case
where a detectable unicode character set is used, such as UTF-8. For
high-ascii characters in a character set other than iso-8859-1, the result
of this patch is undefined.

Fixes #826

The detection of inline images in the mail processor causes inline images to
be removed from the attachment list, if listed there. However, the
attachments in the attachment list were not keyed by the attachment-id, so
there was no proper way to detect and remove the attachments from the list.

This patch properly keys the attachment list by the attachment file_id

Change recent activity date as opposed to create date on ticket view

Fix duplicate phone number (again)

- Tickets will recent replies from the user floats to the top.
- Priority still tops the effective

  * Require a label on form fields
  * Require variable name to be unique per form
  * Fixup duplicate phone numbers on upgrade

This include URLs in embedded links as well as URLs for external images and
videos embedded via iframe elements.

Also add images on pages to the drop-down list for image choosing, and fix
display of images on the client portal.

Fixes #138

Allows the client to be changed on a ticket. Previously, only the
information about the client associated with the ticket was editable. This
patch permits assigning a completely different user to the ticket.