cache the most recently fetched const pointer so we can hand it out more

cache the most recently fetched const pointer so we can hand it out more

2004-06-21  Chris Toshok  <toshok@ximian.com>

	* libebook/e-contact.c (e_contact_get_const): cache the most
	recently fetched const pointer so we can hand it out more than
	once (unless there's an intervening _set).  Should substantially
	lessen the number of allocations we do because of this function.
	(e_contact_set): clear the cached slot for this field, so we'll
	allocate/return a new const string from e_contact_get_const.