Re-working GNCId: removing GNCIdType enum

[Derek Atkins]

In the process ov convertng the GNCId EntityTables to using char*
instead of int, I'm going to get rid of the GNDIdType enumeration.
This implies I'm going to have to un-gwrap it.  Considering nothing
seems to be using that enumeration, I don't think that will be a
big deal, but I thought I'd ask first before I ripped it out...

All the GNC_ID_* definitions will change from enumeration methods to
pre-defined strings.  The GNCIdType will change from typdef enum {}
to typedef char *.  That will allow us to add arbitrary types to
the Book Entity Table. :)

-derek
-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
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