Clear last messages for dumplog between characters

Without this fix, playing a session with one character, saving, then
loading and ending another character in the same session would cause the
former character's last messages to appear in the latter's dumplog.

This fixes issue ComputerScienceHouse#11 on [the DynaHack repo].

(cherry picked from commit 653784f06cdf59b61a04f9ffa4593e45d97e6e0a)

Conflicts:
	libnitrohack/src/decl.c

libnitrohack/src/decl.c

@@ -242,6 +242,8 @@ init_data(void)
     memset(&digging, 0, sizeof (digging));
     memset(&inv_pos, 0, sizeof (inv_pos));
     memset(multi_txt, 0, sizeof (multi_txt));
+    memset(toplines, 0, sizeof(toplines));
+    memset(toplines_count, 0, sizeof(toplines_count));
 
     level = NULL;
     multi = occtime = killer_format = 0;
@@ -270,6 +272,7 @@ init_data(void)
     histevents = NULL;
     histcount = 0;
     timer_id = 1;
+    curline = 0;
 
     program_state.restoring = in_restore;
     iflags.disable_log = nolog;