gpg: Remove warning message for non-implemented search modes.

* kbx/keybox-search.c (keybox_search): Silently ignore.
* doc/specify-user-id.texi: Docuement '@", '+', and '.' search
prefixes.

doc/gpg.texi

@@ -1,4 +1,4 @@
- @c Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
+@c Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
 @c               2008, 2009, 2010 Free Software Foundation, Inc.
 @c This is part of the GnuPG manual.
 @c For copying conditions, see the file gnupg.texi.

doc/specify-user-id.texi

@@ -85,14 +85,14 @@ with left and right angles.
 @end cartouche
 
 
-@item By word match.
-All words must match exactly (not case sensitive) but can appear in any
-order in the user ID or a subjects name.  Words are any sequences of
-letters, digits, the underscore and all characters with bit 7 set.
+@item By partial match on an email address.
+This is indicated by prefixing the search string with an @code{@@}.
+This uses a substring search but considers only the mail address
+(i.e. inside the angle brackets).
 
 @cartouche
 @example
-+Heinrich Heine duesseldorf
+@@heinrichh
 @end example
 @end cartouche
 
@@ -156,8 +156,12 @@ Heine
 @end example
 @end cartouche
 
-@end itemize
+@item . and + prefixes
+These prefixes are reserved for looking up mails anchored at the end
+and for a word search mode.  They are not yet implemented and using
+them is undefined.
 
+@end itemize
 
 Please note that we have reused the hash mark identifier which was used
 in old GnuPG versions to indicate the so called local-id.  It is not

kbx/keybox-search.c

@@ -907,7 +907,7 @@ keybox_search (KEYBOX_HANDLE hd, KEYBOX_SEARCH_DESC *desc, size_t ndesc,
               break;
             case KEYDB_SEARCH_MODE_MAILEND:
             case KEYDB_SEARCH_MODE_WORDS:
-              never_reached (); /* not yet implemented */
+              /* not yet implemented */
               break;
             case KEYDB_SEARCH_MODE_ISSUER:
               if (has_issuer (blob, desc[n].u.name))