Support and use G-line lastmod timestamp.

Support and use G-line lastmod timestamp.

src/gline.c (KEY_LASTMOD): New key string.
  (gline_add): Use new parameter to set lastmod.
  (gline_add_record): Look for KEY_LASTMOD values.
  (gline_write_entry): Set KEY_LASTMOD if lastmod is set.
  (gline_discrim_create): Allow specification of lastmod criteria.
  (gline_discrim_match): Check lastmod if appropriate.

src/gline.h (struct gline): Add lastmod field.
  (struct gline_discrim): Add lastmod fields.
  (gline_add): New parameter.

src/mod-sockcheck.c (sockcheck_issue_gline): Set lastmod.

src/opserv.c (OSMSG_NO_GLINE): New format string.
  (opserv_block): Set lastmod.
  (cmd_gline): Set lastmod.
  (cmd_stats_glines): Allow searching for a particular G-line (just like
    gtrace).
  (opserv_new_user_check): Set lastmod.
  (gtrace_print_func): Use intervals rather than fixed dates and show
    lastmod.

src/opserv.help (GTRACE CRITERIA): Mention lastmod criteria.

src/proto-p10.c (irc_gline): Send lastmod if it is set.
  (cmd_num_gline): Parse out lastmod if it is set.
  (cmd_gline): Parse out lastmod if it is set.
git-archimport-id: srvx@srvx.net--2006/srvx--devo--1.3--patch-32