[C gnus] Abstract out a display-table-specific API (2)

[mike.kupfer at xemacs.org]

COMMIT gnus

This patch has been committed.

2007-12-24  Aidan Kehoe  <kehoea at parhasard.net>

	* lisp/gnus-sum.el:
	* lisp/gnus-sum.el (put-display-table): New.
	* lisp/gnus-sum.el (get-display-table): New.
	Provide with #'defun-when-void, so as to not override the 21.5
	implementation. 
	* lisp/gnus-sum.el (gnus-summary-set-display-table):
	* lisp/gnus-xmas.el (gnus-xmas-summary-set-display-table):
	Use #'put-display-table, not #'aref, to deal with the case where
	the display table is a char table and not a vector.