Support Type definition articles

The fields used for Support Type definition article are shown below to be used in Support initialization.

Article->title: string, label for the type, for example "Change Request"
Article->extra1: string, override the From-field of notes sent as emails sent from this ticket to this value (to prevent exposing of personal email addresses of support persons and to allow single point of collection for the email-import)
Article->extra3: GUID, default SLA for tickets of this type, use GUID of SLA article

Sub-type articles