* g10/tofu.c: Include "sqrtu32.h".
(struct tofu_dbs_s.s): Rename get_trust_gather_other_keys to
get_trust_gather_signature_stats.  Add new field
get_trust_gather_encryption_stats.
(initdb): Create the encryptions table.
(ask_about_binding): Show the encryption statistics too.
(tofu_register): Rename from this...
(tofu_register_signature): ... to this and update callers.
(tofu_register_encryption): New function.
(write_stats_status): Add parameters encryption_count,
encryption_first_done and encryption_most_recent.  Update callers.
Compute the trust using the euclidean distance of the signature and
signature count.  Compare with twice the threshold.  Include
encryption count information in the TFS and TOFU_STATS lines.
(show_statistics): Also get information about the encrypted messages.
* g10/trustdb.c (tdb_get_validity_core): Use it.