Thread entries now have a flexible `format` specification, which allows the
system to save the format alongside the original text. This allows the
system not to have to convert everything to HTML when storing in the
database

Useful if the staff members administratively configure a static password
that the user should never change.

Regardless of the configuration of the help desk registration, allow users
to receive ticket links via email. This patch enables the display and
operation of the ticket access link unless a user login is requested by the
user or specifically required by the system.

This adds a feature for remote authentication methods for clients, such as
LDAP, which will, after successful authentication, yield a
ClientCreateRequest rather than an AuthenticatedUser. The
ClientCreateRequest represents a successful authentication and user
information lookup for a remote client. The client is then presented with a
registration page where their information for their account in the local
system can be reviewed prior to the account creation. Once created, the
client account is confirmed without an email confirmation and is logged in
immediately without reentering a password.

Client accounts now that the user is verified either via staff or the
client's email mailbox, there's a much lower risk to showing a verified user
other tickets and virtually no reason that an administrator should have to
turn the feature on.

This is the mode of the system if account registration is disabled

Instead of always showing the tickets page

For client account / profile updates

This can happen when associated department is private and the system has no
default department (which is possible with v1.6 upgrade)

This can happen when associated department is private and the system has no
default department (which is possible with v1.6 upgrade)

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

Ticket owner as well as collaborators can request access link by entering
email and ticket number.

This reverts commit bc773adb.

Administrators can disable client edits of ticket information. Hopefully,
this will eventually be replaced by role-based ACLs placed on individual
forms and fields.

The concept of extid is being retired to pave-way for customizatable ticket
numbers.