* packet.h, build-packet.c (build_sig_subpkt), export.c

(do_export_stream), import.c (remove_bad_stuff, import), parse-packet.c
(dump_sig_subpkt, parse_one_sig_subpkt): Remove vestigal code for the old
sig cache subpacket.  This wasn't completely harmless as it caused
subpacket 101 to disappear on import and export.

* options.h, armor.c, cipher.c, g10.c, keyedit.c, pkclist.c, sign.c,
encode.c, getkey.c, revoke.c: The current flags for different levels of
PGP-ness are massively complex.  This is step one in simplifying them. No
functional change yet, just use a macro to check for compliance level.

* sign.c (sign_file): Fix bug that causes spurious compression preference
warning.

* sign.c (clearsign_file): Fix bug that prevents proper warning message
from appearing when clearsigning in --pgp2 mode with a non-v3 RSA key.

* main.h, misc.c (compliance_option_string, compliance_string,
compliance_failure), pkclist.c (build_pk_list), sign.c (sign_file,
clearsign_file), encode.c (encode_crypt, write_pubkey_enc_from_list): New
functions to put the "this message may not be usable...." warning in one
place.

* options.h, g10.c (main): Part two of the simplification.  Use a single
enum to indicate what we are compliant to (1991, 2440, PGPx, etc.)

* g10.c (main): Show errors for failure in export, send-keys, recv-keys,
and refresh-keys.

* options.h, g10.c (main): Give algorithm warnings for algorithms chosen
against the --pgpX and --openpgp rules.

* keydb.h, pkclist.c (algo_available): Make TIGER192 invalid in --openpgp
mode.

* sign.c (sign_file), pkclist.c (algo_available): Allow passing a hint of
0.

g10/main.h

@@ -95,6 +95,8 @@ int string_to_compress_algo(const char *string);
 int check_compress_algo(int algo);
 int default_cipher_algo(void);
 int default_compress_algo(void);
+void compliance_failure(void);
+const char *compliance_option_string(void);
 
 /*-- helptext.c --*/
 void display_online_help( const char *keyword );