This is needed to help us remove invalid characters set by some mail
clients.

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

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.

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

Also ensure that the ticket thread is displayed in a <div> container as some
browsers seems to frown upon <iframe>s in <td> elements

Fixes #75

Also remove CSS properties from the style attribute that are browser
specific (like -webkit-* and such)

This provides better compatibility with mPDF, which doesn't support the CSS
white-space:pre-wrap property

Fix preg_replace bugs

Allow for type and encoding specification of the message body and better
describe the integration with custom form fields.

Upgrade to htmLawed 1.1.16

Remove @id attributes as they could confuse existing id attributes used for
styling and javascript.

Remove @class attributes except for standard ones used by Microsoft® office
which have entries in our thread stylesheet.

Some email clients (names omitted to protect the innocent) advertise the
encoding as us-ascii when iso-8859-1 was really implied. This patch allows
the two charsets to be interchangable.

Process inline attachments in thread entry and support inline images in
piped emails

Support inline images across the system, with draft support

Migrate to a single attachment table
    That way we don't need a new table for everything we need to attach an
    inline image to (like a signature, for instance)

Add richtext support for internal notes

Implement images on site pages

* Image paste in Redactor
* Make non-local images optional
* Placeholder for non-local images
* Fix local image download hover
* Don't re-attach inline images

Previously, filenames specified in email headers fetched using the PHP imap
extension were not decoded properly. Specifically, if RFC5987 was used to
encode the filenames, no decoding was performed at all.

This patch properly detects the filename attribute, using a decoding scheme
for RFC5987 if the attribute was encoded properly.

References:
http://osticket.com/forums/showthread.php?t=6129

The administrator can define pages in the admin panel defined as type
'other', and when set to active, those pages can be served from the
/pages/<page-name-slug> URL from the base of the helpdesk.

This is mocked up only against Apache

- Handle decoding large base64 encoded attachments better
- Avoid transcoding from one charset to the same
- Avoid encoding attachments without a declared charset

If the body of an email message is written and encoded with an unrecognized
charset (like 'iso', for instance), then use the original text, assumed to
be 8-bit encoded. This patch will create idiosyncrasies, where text might be
transcoded to utf-8 incorrectly, but it should eliminate instances where
email message bodies are missing due to incorrect charset labels.

Add method to sanitize rich/html text. Addd html encode/decode methods. Remove html encode on display (encoded text saved in db)