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/uhitm.c

@@ -568,6 +568,10 @@ known_hitum(
             if (mon->wormno && *mhit)
                 cutworm(mon, g.bhitpos.x, g.bhitpos.y, slice_or_chop);
         }
+        if (u.uconduct.weaphit && !oldweaphit)
+            livelog_printf(LL_CONDUCT,
+                                 "hit with a wielded weapon for the first time");
+
     }
     return malive;
 }