sipc database interface

Extend sipc so that it will look in a locally configured LDAP database for matches. For example, when typing in 'John Doe' in the 'To:' field of sipc, it would find the appropriate entries and list them in a scroll bar, such as

John Doe 
John Doe 
John Doe

An LDAP interface for Tcl is describe at http://dev.scriptics.com/resource/software/extensions/network/