Chronicle of major events, and livelog

Log game events, such as entering a new dungeon level, breaking
a conduct, or killing a unique monster, in a new "Major events"
chronicle. The entries record the turn when the event happened.
The log can be viewed with #chronicle -command, and the entries
also show up in the end-of-game dump, if that is available.

This feature is on by default, but can be disabled by
defining NO_CHRONICLE compile-time option.

This also contains "live logging", writing the events as they
happen into a single livelog-file. This is mostly useful for
public servers. The livelog is off by default, and must be
compiled in with LIVELOG, and then turned on in sysconf.

Mostly this a version of livelogging from the Hardfought server,
with some changes.

src/pickup.c

@@ -2404,6 +2404,7 @@ in_container(struct obj *obj)
         if (obj->otyp == BAG_OF_HOLDING) /* one bag of holding into another */
             do_boh_explosion(obj, (obj->where == OBJ_FLOOR));
         obfree(obj, (struct obj *) 0);
+        livelog_printf(LL_ACHIEVE, "just blew up %s bag of holding", uhis());
         /* if carried, shop goods will be flagged 'unpaid' and obfree() will
            handle bill issues, but if on floor, we need to put them on bill
            before deleting them (non-shop items will be flagged 'no_charge') */